// File: contracts/ComptrollerInterface.sol

pragma solidity ^0.5.8;

interface ComptrollerInterface {
    /**
     * @notice Marker function used for light validation when updating the comptroller of a market
     * @dev Implementations should simply return true.
     * @return true
     */
    function isComptroller() external view returns (bool);

    /*** Assets You Are In ***/

    function enterMarkets(address[] calldata cTokens) external returns (uint[] memory);
    function exitMarket(address cToken) external returns (uint);

    /*** Policy Hooks ***/

    function mintAllowed(address cToken, address minter, uint mintAmount) external returns (uint);
    function mintVerify(address cToken, address minter, uint mintAmount, uint mintTokens) external;

    function redeemAllowed(address cToken, address redeemer, uint redeemTokens) external returns (uint);
    function redeemVerify(address cToken, address redeemer, uint redeemAmount, uint redeemTokens) external;

    function borrowAllowed(address cToken, address borrower, uint borrowAmount) external returns (uint);
    function borrowVerify(address cToken, address borrower, uint borrowAmount) external;

    function repayBorrowAllowed(
        address cToken,
        address payer,
        address borrower,
        uint repayAmount) external returns (uint);
    function repayBorrowVerify(
        address cToken,
        address payer,
        address borrower,
        uint repayAmount,
        uint borrowerIndex) external;

    function liquidateBorrowAllowed(
        address cTokenBorrowed,
        address cTokenCollateral,
        address liquidator,
        address borrower,
        uint repayAmount) external returns (uint);
    function liquidateBorrowVerify(
        address cTokenBorrowed,
        address cTokenCollateral,
        address liquidator,
        address borrower,
        uint repayAmount,
        uint seizeTokens) external;

    function seizeAllowed(
        address cTokenCollateral,
        address cTokenBorrowed,
        address liquidator,
        address borrower,
        uint seizeTokens) external returns (uint);
    function seizeVerify(
        address cTokenCollateral,
        address cTokenBorrowed,
        address liquidator,
        address borrower,
        uint seizeTokens) external;

    function transferAllowed(address cToken, address src, address dst, uint transferTokens) external returns (uint);
    function transferVerify(address cToken, address src, address dst, uint transferTokens) external;

    /*** Liquidity/Liquidation Calculations ***/

    function liquidateCalculateSeizeTokens(
        address cTokenBorrowed,
        address cTokenCollateral,
        uint repayAmount) external view returns (uint, uint);
}

// File: contracts/ErrorReporter.sol

pragma solidity ^0.5.8;

contract ComptrollerErrorReporter {
    enum Error {
        NO_ERROR,
        UNAUTHORIZED,
        COMPTROLLER_MISMATCH,
        INSUFFICIENT_SHORTFALL,
        INSUFFICIENT_LIQUIDITY,
        INVALID_CLOSE_FACTOR,
        INVALID_COLLATERAL_FACTOR,
        INVALID_LIQUIDATION_INCENTIVE,
        MARKET_NOT_ENTERED,
        MARKET_NOT_LISTED,
        MARKET_ALREADY_LISTED,
        MATH_ERROR,
        NONZERO_BORROW_BALANCE,
        PRICE_ERROR,
        REJECTION,
        SNAPSHOT_ERROR,
        TOO_MANY_ASSETS,
        TOO_MUCH_REPAY
    }

    enum FailureInfo {
        ACCEPT_ADMIN_PENDING_ADMIN_CHECK,
        ACCEPT_PENDING_IMPLEMENTATION_ADDRESS_CHECK,
        EXIT_MARKET_BALANCE_OWED,
        EXIT_MARKET_REJECTION,
        SET_CLOSE_FACTOR_OWNER_CHECK,
        SET_CLOSE_FACTOR_VALIDATION,
        SET_COLLATERAL_FACTOR_OWNER_CHECK,
        SET_COLLATERAL_FACTOR_NO_EXISTS,
        SET_COLLATERAL_FACTOR_VALIDATION,
        SET_COLLATERAL_FACTOR_WITHOUT_PRICE,
        SET_IMPLEMENTATION_OWNER_CHECK,
        SET_LIQUIDATION_INCENTIVE_OWNER_CHECK,
        SET_LIQUIDATION_INCENTIVE_VALIDATION,
        SET_MAX_ASSETS_OWNER_CHECK,
        SET_PENDING_ADMIN_OWNER_CHECK,
        SET_PENDING_IMPLEMENTATION_OWNER_CHECK,
        SET_PRICE_ORACLE_OWNER_CHECK,
        SUPPORT_MARKET_EXISTS,
        SUPPORT_MARKET_OWNER_CHECK,
        ZUNUSED
    }

    /**
      * @dev `error` corresponds to enum Error; `info` corresponds to enum FailureInfo, and `detail` is an arbitrary
      * contract-specific code that enables us to report opaque error codes from upgradeable contracts.
      **/
    event Failure(uint error, uint info, uint detail);

    /**
      * @dev use this when reporting a known error from the money market or a non-upgradeable collaborator
      */
    function fail(Error err, FailureInfo info) internal returns (uint) {
        emit Failure(uint(err), uint(info), 0);

        return uint(err);
    }

    /**
      * @dev use this when reporting an opaque error from an upgradeable collaborator contract
      */
    function failOpaque(Error err, FailureInfo info, uint opaqueError) internal returns (uint) {
        emit Failure(uint(err), uint(info), opaqueError);

        return uint(err);
    }
}

contract TokenErrorReporter {
    enum Error {
        NO_ERROR,
        UNAUTHORIZED,
        BAD_INPUT,
        COMPTROLLER_REJECTION,
        COMPTROLLER_CALCULATION_ERROR,
        INTEREST_RATE_MODEL_ERROR,
        INVALID_ACCOUNT_PAIR,
        INVALID_CLOSE_AMOUNT_REQUESTED,
        INVALID_COLLATERAL_FACTOR,
        MATH_ERROR,
        MARKET_NOT_FRESH,
        MARKET_NOT_LISTED,
        TOKEN_INSUFFICIENT_ALLOWANCE,
        TOKEN_INSUFFICIENT_BALANCE,
        TOKEN_INSUFFICIENT_CASH,
        TOKEN_TRANSFER_IN_FAILED,
        TOKEN_TRANSFER_OUT_FAILED
    }

    /*
     * Note: FailureInfo (but not Error) is kept in alphabetical order
     *       This is because FailureInfo grows significantly faster, and
     *       the order of Error has some meaning, while the order of FailureInfo
     *       is entirely arbitrary.
     */
    enum FailureInfo {
        ACCEPT_ADMIN_PENDING_ADMIN_CHECK,
        ACCRUE_INTEREST_ACCUMULATED_INTEREST_CALCULATION_FAILED,
        ACCRUE_INTEREST_BORROW_RATE_CALCULATION_FAILED,
        ACCRUE_INTEREST_NEW_BORROW_INDEX_CALCULATION_FAILED,
        ACCRUE_INTEREST_NEW_TOTAL_BORROWS_CALCULATION_FAILED,
        ACCRUE_INTEREST_NEW_TOTAL_RESERVES_CALCULATION_FAILED,
        ACCRUE_INTEREST_SIMPLE_INTEREST_FACTOR_CALCULATION_FAILED,
        BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED,
        BORROW_ACCRUE_INTEREST_FAILED,
        BORROW_CASH_NOT_AVAILABLE,
        BORROW_FRESHNESS_CHECK,
        BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED,
        BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED,
        BORROW_MARKET_NOT_LISTED,
        BORROW_COMPTROLLER_REJECTION,
        LIQUIDATE_ACCRUE_BORROW_INTEREST_FAILED,
        LIQUIDATE_ACCRUE_COLLATERAL_INTEREST_FAILED,
        LIQUIDATE_COLLATERAL_FRESHNESS_CHECK,
        LIQUIDATE_COMPTROLLER_REJECTION,
        LIQUIDATE_COMPTROLLER_CALCULATE_AMOUNT_SEIZE_FAILED,
        LIQUIDATE_CLOSE_AMOUNT_IS_UINT_MAX,
        LIQUIDATE_CLOSE_AMOUNT_IS_ZERO,
        LIQUIDATE_FRESHNESS_CHECK,
        LIQUIDATE_LIQUIDATOR_IS_BORROWER,
        LIQUIDATE_REPAY_BORROW_FRESH_FAILED,
        LIQUIDATE_SEIZE_BALANCE_INCREMENT_FAILED,
        LIQUIDATE_SEIZE_BALANCE_DECREMENT_FAILED,
        LIQUIDATE_SEIZE_COMPTROLLER_REJECTION,
        LIQUIDATE_SEIZE_LIQUIDATOR_IS_BORROWER,
        LIQUIDATE_SEIZE_TOO_MUCH,
        MINT_ACCRUE_INTEREST_FAILED,
        MINT_COMPTROLLER_REJECTION,
        MINT_EXCHANGE_CALCULATION_FAILED,
        MINT_EXCHANGE_RATE_READ_FAILED,
        MINT_FRESHNESS_CHECK,
        MINT_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED,
        MINT_NEW_TOTAL_SUPPLY_CALCULATION_FAILED,
        MINT_TRANSFER_IN_FAILED,
        MINT_TRANSFER_IN_NOT_POSSIBLE,
        REDEEM_ACCRUE_INTEREST_FAILED,
        REDEEM_COMPTROLLER_REJECTION,
        REDEEM_EXCHANGE_TOKENS_CALCULATION_FAILED,
        REDEEM_EXCHANGE_AMOUNT_CALCULATION_FAILED,
        REDEEM_EXCHANGE_RATE_READ_FAILED,
        REDEEM_FRESHNESS_CHECK,
        REDEEM_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED,
        REDEEM_NEW_TOTAL_SUPPLY_CALCULATION_FAILED,
        REDEEM_TRANSFER_OUT_NOT_POSSIBLE,
        REDUCE_RESERVES_ACCRUE_INTEREST_FAILED,
        REDUCE_RESERVES_ADMIN_CHECK,
        REDUCE_RESERVES_CASH_NOT_AVAILABLE,
        REDUCE_RESERVES_FRESH_CHECK,
        REDUCE_RESERVES_VALIDATION,
        REPAY_BEHALF_ACCRUE_INTEREST_FAILED,
        REPAY_BORROW_ACCRUE_INTEREST_FAILED,
        REPAY_BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED,
        REPAY_BORROW_COMPTROLLER_REJECTION,
        REPAY_BORROW_FRESHNESS_CHECK,
        REPAY_BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED,
        REPAY_BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED,
        REPAY_BORROW_TRANSFER_IN_NOT_POSSIBLE,
        SET_COLLATERAL_FACTOR_OWNER_CHECK,
        SET_COLLATERAL_FACTOR_VALIDATION,
        SET_COMPTROLLER_OWNER_CHECK,
        SET_INTEREST_RATE_MODEL_ACCRUE_INTEREST_FAILED,
        SET_INTEREST_RATE_MODEL_FRESH_CHECK,
        SET_INTEREST_RATE_MODEL_OWNER_CHECK,
        SET_MAX_ASSETS_OWNER_CHECK,
        SET_ORACLE_MARKET_NOT_LISTED,
        SET_PENDING_ADMIN_OWNER_CHECK,
        SET_RESERVE_FACTOR_ACCRUE_INTEREST_FAILED,
        SET_RESERVE_FACTOR_ADMIN_CHECK,
        SET_RESERVE_FACTOR_FRESH_CHECK,
        SET_RESERVE_FACTOR_BOUNDS_CHECK,
        TRANSFER_COMPTROLLER_REJECTION,
        TRANSFER_NOT_ALLOWED,
        TRANSFER_NOT_ENOUGH,
        TRANSFER_TOO_MUCH
    }

    /**
      * @dev `error` corresponds to enum Error; `info` corresponds to enum FailureInfo, and `detail` is an arbitrary
      * contract-specific code that enables us to report opaque error codes from upgradeable contracts.
      **/
    event Failure(uint error, uint info, uint detail);

    /**
      * @dev use this when reporting a known error from the money market or a non-upgradeable collaborator
      */
    function fail(Error err, FailureInfo info) internal returns (uint) {
        emit Failure(uint(err), uint(info), 0);

        return uint(err);
    }

    /**
      * @dev use this when reporting an opaque error from an upgradeable collaborator contract
      */
    function failOpaque(Error err, FailureInfo info, uint opaqueError) internal returns (uint) {
        emit Failure(uint(err), uint(info), opaqueError);

        return uint(err);
    }
}

// File: contracts/CarefulMath.sol

pragma solidity ^0.5.8;

/**
  * @title Careful Math
  * @author Compound
  * @notice Derived from OpenZeppelin's SafeMath library
  *         https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/contracts/math/SafeMath.sol
  */
contract CarefulMath {

    /**
     * @dev Possible error codes that we can return
     */
    enum MathError {
        NO_ERROR,
        DIVISION_BY_ZERO,
        INTEGER_OVERFLOW,
        INTEGER_UNDERFLOW
    }

    /**
    * @dev Multiplies two numbers, returns an error on overflow.
    */
    function mulUInt(uint a, uint b) internal pure returns (MathError, uint) {
        if (a == 0) {
            return (MathError.NO_ERROR, 0);
        }

        uint c = a * b;

        if (c / a != b) {
            return (MathError.INTEGER_OVERFLOW, 0);
        } else {
            return (MathError.NO_ERROR, c);
        }
    }

    /**
    * @dev Integer division of two numbers, truncating the quotient.
    */
    function divUInt(uint a, uint b) internal pure returns (MathError, uint) {
        if (b == 0) {
            return (MathError.DIVISION_BY_ZERO, 0);
        }

        return (MathError.NO_ERROR, a / b);
    }

    /**
    * @dev Subtracts two numbers, returns an error on overflow (i.e. if subtrahend is greater than minuend).
    */
    function subUInt(uint a, uint b) internal pure returns (MathError, uint) {
        if (b <= a) {
            return (MathError.NO_ERROR, a - b);
        } else {
            return (MathError.INTEGER_UNDERFLOW, 0);
        }
    }

    /**
    * @dev Adds two numbers, returns an error on overflow.
    */
    function addUInt(uint a, uint b) internal pure returns (MathError, uint) {
        uint c = a + b;

        if (c >= a) {
            return (MathError.NO_ERROR, c);
        } else {
            return (MathError.INTEGER_OVERFLOW, 0);
        }
    }

    /**
    * @dev add a and b and then subtract c
    */
    function addThenSubUInt(uint a, uint b, uint c) internal pure returns (MathError, uint) {
        (MathError err0, uint sum) = addUInt(a, b);

        if (err0 != MathError.NO_ERROR) {
            return (err0, 0);
        }

        return subUInt(sum, c);
    }
}

// File: contracts/Exponential.sol

pragma solidity ^0.5.8;


/**
 * @title Exponential module for storing fixed-decision decimals
 * @author Compound
 * @notice Exp is a struct which stores decimals with a fixed precision of 18 decimal places.
 *         Thus, if we wanted to store the 5.1, mantissa would store 5.1e18. That is:
 *         `Exp({mantissa: 5100000000000000000})`.
 */
contract Exponential is CarefulMath {
    uint constant expScale = 1e18;
    uint constant halfExpScale = expScale/2;
    uint constant mantissaOne = expScale;

    struct Exp {
        uint mantissa;
    }

    /**
     * @dev Creates an exponential from numerator and denominator values.
     *      Note: Returns an error if (`num` * 10e18) > MAX_INT,
     *            or if `denom` is zero.
     */
    function getExp(uint num, uint denom) pure internal returns (MathError, Exp memory) {
        (MathError err0, uint scaledNumerator) = mulUInt(num, expScale);
        if (err0 != MathError.NO_ERROR) {
            return (err0, Exp({mantissa: 0}));
        }

        (MathError err1, uint rational) = divUInt(scaledNumerator, denom);
        if (err1 != MathError.NO_ERROR) {
            return (err1, Exp({mantissa: 0}));
        }

        return (MathError.NO_ERROR, Exp({mantissa: rational}));
    }

    /**
     * @dev Adds two exponentials, returning a new exponential.
     */
    function addExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {
        (MathError error, uint result) = addUInt(a.mantissa, b.mantissa);

        return (error, Exp({mantissa: result}));
    }

    /**
     * @dev Subtracts two exponentials, returning a new exponential.
     */
    function subExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {
        (MathError error, uint result) = subUInt(a.mantissa, b.mantissa);

        return (error, Exp({mantissa: result}));
    }

    /**
     * @dev Multiply an Exp by a scalar, returning a new Exp.
     */
    function mulScalar(Exp memory a, uint scalar) pure internal returns (MathError, Exp memory) {
        (MathError err0, uint scaledMantissa) = mulUInt(a.mantissa, scalar);
        if (err0 != MathError.NO_ERROR) {
            return (err0, Exp({mantissa: 0}));
        }

        return (MathError.NO_ERROR, Exp({mantissa: scaledMantissa}));
    }

    /**
     * @dev Multiply an Exp by a scalar, then truncate to return an unsigned integer.
     */
    function mulScalarTruncate(Exp memory a, uint scalar) pure internal returns (MathError, uint) {
        (MathError err, Exp memory product) = mulScalar(a, scalar);
        if (err != MathError.NO_ERROR) {
            return (err, 0);
        }

        return (MathError.NO_ERROR, truncate(product));
    }

    /**
     * @dev Multiply an Exp by a scalar, truncate, then add an to an unsigned integer, returning an unsigned integer.
     */
    function mulScalarTruncateAddUInt(Exp memory a, uint scalar, uint addend) pure internal returns (MathError, uint) {
        (MathError err, Exp memory product) = mulScalar(a, scalar);
        if (err != MathError.NO_ERROR) {
            return (err, 0);
        }

        return addUInt(truncate(product), addend);
    }

    /**
     * @dev Divide an Exp by a scalar, returning a new Exp.
     */
    function divScalar(Exp memory a, uint scalar) pure internal returns (MathError, Exp memory) {
        (MathError err0, uint descaledMantissa) = divUInt(a.mantissa, scalar);
        if (err0 != MathError.NO_ERROR) {
            return (err0, Exp({mantissa: 0}));
        }

        return (MathError.NO_ERROR, Exp({mantissa: descaledMantissa}));
    }

    /**
     * @dev Divide a scalar by an Exp, returning a new Exp.
     */
    function divScalarByExp(uint scalar, Exp memory divisor) pure internal returns (MathError, Exp memory) {
        /*
          We are doing this as:
          getExp(mulUInt(expScale, scalar), divisor.mantissa)

          How it works:
          Exp = a / b;
          Scalar = s;
          `s / (a / b)` = `b * s / a` and since for an Exp `a = mantissa, b = expScale`
        */
        (MathError err0, uint numerator) = mulUInt(expScale, scalar);
        if (err0 != MathError.NO_ERROR) {
            return (err0, Exp({mantissa: 0}));
        }
        return getExp(numerator, divisor.mantissa);
    }

    /**
     * @dev Divide a scalar by an Exp, then truncate to return an unsigned integer.
     */
    function divScalarByExpTruncate(uint scalar, Exp memory divisor) pure internal returns (MathError, uint) {
        (MathError err, Exp memory fraction) = divScalarByExp(scalar, divisor);
        if (err != MathError.NO_ERROR) {
            return (err, 0);
        }

        return (MathError.NO_ERROR, truncate(fraction));
    }

    /**
     * @dev Multiplies two exponentials, returning a new exponential.
     */
    function mulExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {

        (MathError err0, uint doubleScaledProduct) = mulUInt(a.mantissa, b.mantissa);
        if (err0 != MathError.NO_ERROR) {
            return (err0, Exp({mantissa: 0}));
        }

        // We add half the scale before dividing so that we get rounding instead of truncation.
        //  See "Listing 6" and text above it at https://accu.org/index.php/journals/1717
        // Without this change, a result like 6.6...e-19 will be truncated to 0 instead of being rounded to 1e-18.
        (MathError err1, uint doubleScaledProductWithHalfScale) = addUInt(halfExpScale, doubleScaledProduct);
        if (err1 != MathError.NO_ERROR) {
            return (err1, Exp({mantissa: 0}));
        }

        (MathError err2, uint product) = divUInt(doubleScaledProductWithHalfScale, expScale);
        // The only error `div` can return is MathError.DIVISION_BY_ZERO but we control `expScale` and it is not zero.
        assert(err2 == MathError.NO_ERROR);

        return (MathError.NO_ERROR, Exp({mantissa: product}));
    }

    /**
     * @dev Multiplies two exponentials given their mantissas, returning a new exponential.
     */
    function mulExp(uint a, uint b) pure internal returns (MathError, Exp memory) {
        return mulExp(Exp({mantissa: a}), Exp({mantissa: b}));
    }

    /**
     * @dev Multiplies three exponentials, returning a new exponential.
     */
    function mulExp3(Exp memory a, Exp memory b, Exp memory c) pure internal returns (MathError, Exp memory) {
        (MathError err, Exp memory ab) = mulExp(a, b);
        if (err != MathError.NO_ERROR) {
            return (err, ab);
        }
        return mulExp(ab, c);
    }

    /**
     * @dev Divides two exponentials, returning a new exponential.
     *     (a/scale) / (b/scale) = (a/scale) * (scale/b) = a/b,
     *  which we can scale as an Exp by calling getExp(a.mantissa, b.mantissa)
     */
    function divExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {
        return getExp(a.mantissa, b.mantissa);
    }

    /**
     * @dev Truncates the given exp to a whole number value.
     *      For example, truncate(Exp{mantissa: 15 * expScale}) = 15
     */
    function truncate(Exp memory exp) pure internal returns (uint) {
        // Note: We are not using careful math here as we're performing a division that cannot fail
        return exp.mantissa / expScale;
    }

    /**
     * @dev Checks if first Exp is less than second Exp.
     */
    function lessThanExp(Exp memory left, Exp memory right) pure internal returns (bool) {
        return left.mantissa < right.mantissa; //TODO: Add some simple tests and this in another PR yo.
    }

    /**
     * @dev Checks if left Exp <= right Exp.
     */
    function lessThanOrEqualExp(Exp memory left, Exp memory right) pure internal returns (bool) {
        return left.mantissa <= right.mantissa;
    }

    /**
     * @dev returns true if Exp is exactly zero
     */
    function isZeroExp(Exp memory value) pure internal returns (bool) {
        return value.mantissa == 0;
    }
}

// File: contracts/EIP20Interface.sol

pragma solidity ^0.5.8;

/**
 * @title ERC 20 Token Standard Interface
 *  https://eips.ethereum.org/EIPS/eip-20
 */
interface EIP20Interface {

    /**
      * @notice Get the total number of tokens in circulation
      * @return The supply of tokens
      */
    function totalSupply() external view returns (uint256);

    /**
     * @notice Gets the balance of the specified address
     * @param owner The address from which the balance will be retrieved
     * @return The balance
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    /**
      * @notice Transfer `amount` tokens from `msg.sender` to `dst`
      * @param dst The address of the destination account
      * @param amount The number of tokens to transfer
      * @return Whether or not the transfer succeeded
      */
    function transfer(address dst, uint256 amount) external returns (bool success);

    /**
      * @notice Transfer `amount` tokens from `src` to `dst`
      * @param src The address of the source account
      * @param dst The address of the destination account
      * @param amount The number of tokens to transfer
      * @return Whether or not the transfer succeeded
      */
    function transferFrom(address src, address dst, uint256 amount) external returns (bool success);

    /**
      * @notice Approve `spender` to transfer up to `amount` from `src`
      * @dev This will overwrite the approval amount for `spender`
      *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
      * @param spender The address of the account which may transfer tokens
      * @param amount The number of tokens that are approved (-1 means infinite)
      * @return Whether or not the approval succeeded
      */
    function approve(address spender, uint256 amount) external returns (bool success);

    /**
      * @notice Get the current allowance from `owner` for `spender`
      * @param owner The address of the account which owns the tokens to be spent
      * @param spender The address of the account which may transfer tokens
      * @return The number of tokens allowed to be spent (-1 means infinite)
      */
    function allowance(address owner, address spender) external view returns (uint256 remaining);

    event Transfer(address indexed from, address indexed to, uint256 amount);
    event Approval(address indexed owner, address indexed spender, uint256 amount);
}

// File: contracts/EIP20NonStandardInterface.sol

pragma solidity ^0.5.8;

/**
 * @title EIP20NonStandardInterface
 * @dev Version of ERC20 with no return values for `transfer` and `transferFrom`
 *  See https://medium.com/coinmonks/missing-return-value-bug-at-least-130-tokens-affected-d67bf08521ca
 */
interface EIP20NonStandardInterface {

    /**
     * @notice Get the total number of tokens in circulation
     * @return The supply of tokens
     */
    function totalSupply() external view returns (uint256);

    /**
     * @notice Gets the balance of the specified address
     * @param owner The address from which the balance will be retrieved
     * @return The balance
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    ///
    /// !!!!!!!!!!!!!!
    /// !!! NOTICE !!! `transfer` does not return a value, in violation of the ERC-20 specification
    /// !!!!!!!!!!!!!!
    ///

    /**
      * @notice Transfer `amount` tokens from `msg.sender` to `dst`
      * @param dst The address of the destination account
      * @param amount The number of tokens to transfer
      */
    function transfer(address dst, uint256 amount) external;

    ///
    /// !!!!!!!!!!!!!!
    /// !!! NOTICE !!! `transferFrom` does not return a value, in violation of the ERC-20 specification
    /// !!!!!!!!!!!!!!
    ///

    /**
      * @notice Transfer `amount` tokens from `src` to `dst`
      * @param src The address of the source account
      * @param dst The address of the destination account
      * @param amount The number of tokens to transfer
      */
    function transferFrom(address src, address dst, uint256 amount) external;

    /**
      * @notice Approve `spender` to transfer up to `amount` from `src`
      * @dev This will overwrite the approval amount for `spender`
      *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
      * @param spender The address of the account which may transfer tokens
      * @param amount The number of tokens that are approved
      * @return Whether or not the approval succeeded
      */
    function approve(address spender, uint256 amount) external returns (bool success);

    /**
      * @notice Get the current allowance from `owner` for `spender`
      * @param owner The address of the account which owns the tokens to be spent
      * @param spender The address of the account which may transfer tokens
      * @return The number of tokens allowed to be spent
      */
    function allowance(address owner, address spender) external view returns (uint256 remaining);

    event Transfer(address indexed from, address indexed to, uint256 amount);
    event Approval(address indexed owner, address indexed spender, uint256 amount);
}

// File: contracts/ReentrancyGuard.sol

pragma solidity ^0.5.8;

/**
 * @title Helps contracts guard against reentrancy attacks.
 * @author Remco Bloemen <remco@2π.com>, Eenae <[email protected]>
 * @dev If you mark a function `nonReentrant`, you should also
 * mark it `external`.
 */
contract ReentrancyGuard {
    /// @dev counter to allow mutex lock with only one SSTORE operation
    uint256 private _guardCounter;

    constructor () internal {
        // The counter starts at one to prevent changing it from zero to a non-zero
        // value, which is a more expensive operation.
        _guardCounter = 1;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        _guardCounter += 1;
        uint256 localCounter = _guardCounter;
        _;
        require(localCounter == _guardCounter, "re-entered");
    }
}

// File: contracts/InterestRateModel.sol

pragma solidity ^0.5.8;

/**
  * @title The Compound InterestRateModel Interface
  * @author Compound
  * @notice Any interest rate model should derive from this contract.
  * @dev These functions are specifically not marked `pure` as implementations of this
  *      contract may read from storage variables.
  */
interface InterestRateModel {
    /**
      * @notice Gets the current borrow interest rate based on the given asset, total cash, total borrows
      *         and total reserves.
      * @dev The return value should be scaled by 1e18, thus a return value of
      *      `(true, 1000000000000)` implies an interest rate of 0.000001 or 0.0001% *per block*.
      * @param cash The total cash of the underlying asset in the CToken
      * @param borrows The total borrows of the underlying asset in the CToken
      * @param reserves The total reserves of the underlying asset in the CToken
      * @return Success or failure and the borrow interest rate per block scaled by 10e18
      */
    function getBorrowRate(uint cash, uint borrows, uint reserves) external view returns (uint, uint);

    /**
      * @notice Marker function used for light validation when updating the interest rate model of a market
      * @dev Marker function used for light validation when updating the interest rate model of a market. Implementations should simply return true.
      * @return Success or failure
      */
    function isInterestRateModel() external view returns (bool);
}

// File: contracts/CToken.sol

pragma solidity ^0.5.8;








/**
 * @title Compound's CToken Contract
 * @notice Abstract base for CTokens
 * @author Compound
 */
contract CToken is EIP20Interface, Exponential, TokenErrorReporter, ReentrancyGuard {
    /**
     * @notice Indicator that this is a CToken contract (for inspection)
     */
    bool public constant isCToken = true;

    /**
     * @notice EIP-20 token name for this token
     */
    string public name;

    /**
     * @notice EIP-20 token symbol for this token
     */
    string public symbol;

    /**
     * @notice EIP-20 token decimals for this token
     */
    uint public decimals;

    /**
     * @notice Maximum borrow rate that can ever be applied (.0005% / block)
     */
    uint constant borrowRateMaxMantissa = 5e14;

    /**
     * @notice Maximum fraction of interest that can be set aside for reserves
     */
    uint constant reserveFactorMaxMantissa = 1e18;

    /**
     * @notice Administrator for this contract
     */
    address payable public admin;

    /**
     * @notice Pending administrator for this contract
     */
    address payable public pendingAdmin;

    /**
     * @notice Contract which oversees inter-cToken operations
     */
    ComptrollerInterface public comptroller;

    /**
     * @notice Model which tells what the current interest rate should be
     */
    InterestRateModel public interestRateModel;

    /**
     * @notice Initial exchange rate used when minting the first CTokens (used when totalSupply = 0)
     */
    uint public initialExchangeRateMantissa;

    /**
     * @notice Fraction of interest currently set aside for reserves
     */
    uint public reserveFactorMantissa;

    /**
     * @notice Block number that interest was last accrued at
     */
    uint public accrualBlockNumber;

    /**
     * @notice Accumulator of total earned interest since the opening of the market
     */
    uint public borrowIndex;

    /**
     * @notice Total amount of outstanding borrows of the underlying in this market
     */
    uint public totalBorrows;

    /**
     * @notice Total amount of reserves of the underlying held in this market
     */
    uint public totalReserves;

    /**
     * @notice Total number of tokens in circulation
     */
    uint256 public totalSupply;

    /**
     * @notice Official record of token balances for each account
     */
    mapping (address => uint256) accountTokens;

    /**
     * @notice Approved token transfer amounts on behalf of others
     */
    mapping (address => mapping (address => uint256)) transferAllowances;

    /**
     * @notice Container for borrow balance information
     * @member principal Total balance (with accrued interest), after applying the most recent balance-changing action
     * @member interestIndex Global borrowIndex as of the most recent balance-changing action
     */
    struct BorrowSnapshot {
        uint principal;
        uint interestIndex;
    }

    /**
     * @notice Mapping of account addresses to outstanding borrow balances
     */
    mapping(address => BorrowSnapshot) accountBorrows;


    /*** Market Events ***/

    /**
     * @notice Event emitted when interest is accrued
     */
    event AccrueInterest(uint interestAccumulated, uint borrowIndex, uint totalBorrows);

    /**
     * @notice Event emitted when tokens are minted
     */
    event Mint(address minter, uint mintAmount, uint mintTokens);

    /**
     * @notice Event emitted when tokens are redeemed
     */
    event Redeem(address redeemer, uint redeemAmount, uint redeemTokens);

    /**
     * @notice Event emitted when underlying is borrowed
     */
    event Borrow(address borrower, uint borrowAmount, uint accountBorrows, uint totalBorrows);

    /**
     * @notice Event emitted when a borrow is repaid
     */
    event RepayBorrow(address payer, address borrower, uint repayAmount, uint accountBorrows, uint totalBorrows);

    /**
     * @notice Event emitted when a borrow is liquidated
     */
    event LiquidateBorrow(address liquidator, address borrower, uint repayAmount, address cTokenCollateral, uint seizeTokens);


    /*** Admin Events ***/

    /**
     * @notice Event emitted when pendingAdmin is changed
     */
    event NewPendingAdmin(address oldPendingAdmin, address newPendingAdmin);

    /**
     * @notice Event emitted when pendingAdmin is accepted, which means admin is updated
     */
    event NewAdmin(address oldAdmin, address newAdmin);

    /**
     * @notice Event emitted when comptroller is changed
     */
    event NewComptroller(ComptrollerInterface oldComptroller, ComptrollerInterface newComptroller);

    /**
     * @notice Event emitted when interestRateModel is changed
     */
    event NewMarketInterestRateModel(InterestRateModel oldInterestRateModel, InterestRateModel newInterestRateModel);

    /**
     * @notice Event emitted when the reserve factor is changed
     */
    event NewReserveFactor(uint oldReserveFactorMantissa, uint newReserveFactorMantissa);

    /**
     * @notice Event emitted when the reserves are reduced
     */
    event ReservesReduced(address admin, uint reduceAmount, uint newTotalReserves);


    /**
     * @notice Construct a new money market
     * @param comptroller_ The address of the Comptroller
     * @param interestRateModel_ The address of the interest rate model
     * @param initialExchangeRateMantissa_ The initial exchange rate, scaled by 1e18
     * @param name_ EIP-20 name of this token
     * @param symbol_ EIP-20 symbol of this token
     * @param decimals_ EIP-20 decimal precision of this token
     */
    constructor(ComptrollerInterface comptroller_,
                InterestRateModel interestRateModel_,
                uint initialExchangeRateMantissa_,
                string memory name_,
                string memory symbol_,
                uint decimals_) internal {
        // Set admin to msg.sender
        admin = msg.sender;

        // Set initial exchange rate
        initialExchangeRateMantissa = initialExchangeRateMantissa_;
        require(initialExchangeRateMantissa > 0, "Initial exchange rate must be greater than zero.");

        // Set the comptroller
        uint err = _setComptroller(comptroller_);
        require(err == uint(Error.NO_ERROR), "Setting comptroller failed");

        // Initialize block number and borrow index (block number mocks depend on comptroller being set)
        accrualBlockNumber = getBlockNumber();
        borrowIndex = mantissaOne;

        // Set the interest rate model (depends on block number / borrow index)
        err = _setInterestRateModelFresh(interestRateModel_);
        require(err == uint(Error.NO_ERROR), "Setting interest rate model failed");

        name = name_;
        symbol = symbol_;
        decimals = decimals_;
    }

    /**
     * @notice Transfer `tokens` tokens from `src` to `dst` by `spender`
     * @dev Called by both `transfer` and `transferFrom` internally
     * @param spender The address of the account performing the transfer
     * @param src The address of the source account
     * @param dst The address of the destination account
     * @param tokens The number of tokens to transfer
     * @return Whether or not the transfer succeeded
     */
    function transferTokens(address spender, address src, address dst, uint tokens) internal returns (uint) {
        /* Fail if transfer not allowed */
        uint allowed = comptroller.transferAllowed(address(this), src, dst, tokens);
        if (allowed != 0) {
            return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.TRANSFER_COMPTROLLER_REJECTION, allowed);
        }

        /* Do not allow self-transfers */
        if (src == dst) {
            return fail(Error.BAD_INPUT, FailureInfo.TRANSFER_NOT_ALLOWED);
        }

        /* Get the allowance, infinite for the account owner */
        uint startingAllowance = 0;
        if (spender == src) {
            startingAllowance = uint(-1);
        } else {
            startingAllowance = transferAllowances[src][spender];
        }

        /* Do the calculations, checking for {under,over}flow */
        MathError mathErr;
        uint allowanceNew;
        uint srcTokensNew;
        uint dstTokensNew;

        (mathErr, allowanceNew) = subUInt(startingAllowance, tokens);
        if (mathErr != MathError.NO_ERROR) {
            return fail(Error.MATH_ERROR, FailureInfo.TRANSFER_NOT_ALLOWED);
        }

        (mathErr, srcTokensNew) = subUInt(accountTokens[src], tokens);
        if (mathErr != MathError.NO_ERROR) {
            return fail(Error.MATH_ERROR, FailureInfo.TRANSFER_NOT_ENOUGH);
        }

        (mathErr, dstTokensNew) = addUInt(accountTokens[dst], tokens);
        if (mathErr != MathError.NO_ERROR) {
            return fail(Error.MATH_ERROR, FailureInfo.TRANSFER_TOO_MUCH);
        }

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        accountTokens[src] = srcTokensNew;
        accountTokens[dst] = dstTokensNew;

        /* Eat some of the allowance (if necessary) */
        if (startingAllowance != uint(-1)) {
            transferAllowances[src][spender] = allowanceNew;
        }

        /* We emit a Transfer event */
        emit Transfer(src, dst, tokens);

        /* We call the defense hook (which checks for under-collateralization) */
        comptroller.transferVerify(address(this), src, dst, tokens);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Transfer `amount` tokens from `msg.sender` to `dst`
     * @param dst The address of the destination account
     * @param amount The number of tokens to transfer
     * @return Whether or not the transfer succeeded
     */
    function transfer(address dst, uint256 amount) external nonReentrant returns (bool) {
        return transferTokens(msg.sender, msg.sender, dst, amount) == uint(Error.NO_ERROR);
    }

    /**
     * @notice Transfer `amount` tokens from `src` to `dst`
     * @param src The address of the source account
     * @param dst The address of the destination account
     * @param amount The number of tokens to transfer
     * @return Whether or not the transfer succeeded
     */
    function transferFrom(address src, address dst, uint256 amount) external nonReentrant returns (bool) {
        return transferTokens(msg.sender, src, dst, amount) == uint(Error.NO_ERROR);
    }

    /**
     * @notice Approve `spender` to transfer up to `amount` from `src`
     * @dev This will overwrite the approval amount for `spender`
     *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
     * @param spender The address of the account which may transfer tokens
     * @param amount The number of tokens that are approved (-1 means infinite)
     * @return Whether or not the approval succeeded
     */
    function approve(address spender, uint256 amount) external returns (bool) {
        address src = msg.sender;
        transferAllowances[src][spender] = amount;
        emit Approval(src, spender, amount);
        return true;
    }

    /**
     * @notice Get the current allowance from `owner` for `spender`
     * @param owner The address of the account which owns the tokens to be spent
     * @param spender The address of the account which may transfer tokens
     * @return The number of tokens allowed to be spent (-1 means infinite)
     */
    function allowance(address owner, address spender) external view returns (uint256) {
        return transferAllowances[owner][spender];
    }

    /**
     * @notice Get the token balance of the `owner`
     * @param owner The address of the account to query
     * @return The number of tokens owned by `owner`
     */
    function balanceOf(address owner) external view returns (uint256) {
        return accountTokens[owner];
    }

    /**
     * @notice Get the underlying balance of the `owner`
     * @dev This also accrues interest in a transaction
     * @param owner The address of the account to query
     * @return The amount of underlying owned by `owner`
     */
    function balanceOfUnderlying(address owner) external returns (uint) {
        Exp memory exchangeRate = Exp({mantissa: exchangeRateCurrent()});
        (MathError mErr, uint balance) = mulScalarTruncate(exchangeRate, accountTokens[owner]);
        require(mErr == MathError.NO_ERROR);
        return balance;
    }

    /**
     * @notice Get a snapshot of the account's balances, and the cached exchange rate
     * @dev This is used by comptroller to more efficiently perform liquidity checks.
     * @param account Address of the account to snapshot
     * @return (possible error, token balance, borrow balance, exchange rate mantissa)
     */
    function getAccountSnapshot(address account) external view returns (uint, uint, uint, uint) {
        uint cTokenBalance = accountTokens[account];
        uint borrowBalance;
        uint exchangeRateMantissa;

        MathError mErr;

        (mErr, borrowBalance) = borrowBalanceStoredInternal(account);
        if (mErr != MathError.NO_ERROR) {
            return (uint(Error.MATH_ERROR), 0, 0, 0);
        }

        (mErr, exchangeRateMantissa) = exchangeRateStoredInternal();
        if (mErr != MathError.NO_ERROR) {
            return (uint(Error.MATH_ERROR), 0, 0, 0);
        }

        return (uint(Error.NO_ERROR), cTokenBalance, borrowBalance, exchangeRateMantissa);
    }

    /**
     * @dev Function to simply retrieve block number
     *  This exists mainly for inheriting test contracts to stub this result.
     */
    function getBlockNumber() internal view returns (uint) {
        return block.number;
    }

    /**
     * @notice Returns the current per-block borrow interest rate for this cToken
     * @return The borrow interest rate per block, scaled by 1e18
     */
    function borrowRatePerBlock() external view returns (uint) {
        (uint opaqueErr, uint borrowRateMantissa) = interestRateModel.getBorrowRate(getCashPrior(), totalBorrows, totalReserves);
        require(opaqueErr == 0, "borrowRatePerBlock: interestRateModel.borrowRate failed"); // semi-opaque
        return borrowRateMantissa;
    }

    /**
     * @notice Returns the current per-block supply interest rate for this cToken
     * @return The supply interest rate per block, scaled by 1e18
     */
    function supplyRatePerBlock() external view returns (uint) {
        /* We calculate the supply rate:
         *  underlying = totalSupply × exchangeRate
         *  borrowsPer = totalBorrows ÷ underlying
         *  supplyRate = borrowRate × (1-reserveFactor) × borrowsPer
         */
        uint exchangeRateMantissa = exchangeRateStored();

        (uint e0, uint borrowRateMantissa) = interestRateModel.getBorrowRate(getCashPrior(), totalBorrows, totalReserves);
        require(e0 == 0, "supplyRatePerBlock: calculating borrowRate failed"); // semi-opaque

        (MathError e1, Exp memory underlying) = mulScalar(Exp({mantissa: exchangeRateMantissa}), totalSupply);
        require(e1 == MathError.NO_ERROR, "supplyRatePerBlock: calculating underlying failed");

        (MathError e2, Exp memory borrowsPer) = divScalarByExp(totalBorrows, underlying);
        require(e2 == MathError.NO_ERROR, "supplyRatePerBlock: calculating borrowsPer failed");

        (MathError e3, Exp memory oneMinusReserveFactor) = subExp(Exp({mantissa: mantissaOne}), Exp({mantissa: reserveFactorMantissa}));
        require(e3 == MathError.NO_ERROR, "supplyRatePerBlock: calculating oneMinusReserveFactor failed");

        (MathError e4, Exp memory supplyRate) = mulExp3(Exp({mantissa: borrowRateMantissa}), oneMinusReserveFactor, borrowsPer);
        require(e4 == MathError.NO_ERROR, "supplyRatePerBlock: calculating supplyRate failed");

        return supplyRate.mantissa;
    }

    /**
     * @notice Returns the current total borrows plus accrued interest
     * @return The total borrows with interest
     */
    function totalBorrowsCurrent() external nonReentrant returns (uint) {
        require(accrueInterest() == uint(Error.NO_ERROR), "accrue interest failed");
        return totalBorrows;
    }

    /**
     * @notice Accrue interest to updated borrowIndex and then calculate account's borrow balance using the updated borrowIndex
     * @param account The address whose balance should be calculated after updating borrowIndex
     * @return The calculated balance
     */
    function borrowBalanceCurrent(address account) external nonReentrant returns (uint) {
        require(accrueInterest() == uint(Error.NO_ERROR), "accrue interest failed");
        return borrowBalanceStored(account);
    }

    /**
     * @notice Return the borrow balance of account based on stored data
     * @param account The address whose balance should be calculated
     * @return The calculated balance
     */
    function borrowBalanceStored(address account) public view returns (uint) {
        (MathError err, uint result) = borrowBalanceStoredInternal(account);
        require(err == MathError.NO_ERROR, "borrowBalanceStored: borrowBalanceStoredInternal failed");
        return result;
    }

    /**
     * @notice Return the borrow balance of account based on stored data
     * @param account The address whose balance should be calculated
     * @return (error code, the calculated balance or 0 if error code is non-zero)
     */
    function borrowBalanceStoredInternal(address account) internal view returns (MathError, uint) {
        /* Note: we do not assert that the market is up to date */
        MathError mathErr;
        uint principalTimesIndex;
        uint result;

        /* Get borrowBalance and borrowIndex */
        BorrowSnapshot storage borrowSnapshot = accountBorrows[account];

        /* If borrowBalance = 0 then borrowIndex is likely also 0.
         * Rather than failing the calculation with a division by 0, we immediately return 0 in this case.
         */
        if (borrowSnapshot.principal == 0) {
            return (MathError.NO_ERROR, 0);
        }

        /* Calculate new borrow balance using the interest index:
         *  recentBorrowBalance = borrower.borrowBalance * market.borrowIndex / borrower.borrowIndex
         */
        (mathErr, principalTimesIndex) = mulUInt(borrowSnapshot.principal, borrowIndex);
        if (mathErr != MathError.NO_ERROR) {
            return (mathErr, 0);
        }

        (mathErr, result) = divUInt(principalTimesIndex, borrowSnapshot.interestIndex);
        if (mathErr != MathError.NO_ERROR) {
            return (mathErr, 0);
        }

        return (MathError.NO_ERROR, result);
    }

    /**
     * @notice Accrue interest then return the up-to-date exchange rate
     * @return Calculated exchange rate scaled by 1e18
     */
    function exchangeRateCurrent() public nonReentrant returns (uint) {
        require(accrueInterest() == uint(Error.NO_ERROR), "accrue interest failed");
        return exchangeRateStored();
    }

    /**
     * @notice Calculates the exchange rate from the underlying to the CToken
     * @dev This function does not accrue interest before calculating the exchange rate
     * @return Calculated exchange rate scaled by 1e18
     */
    function exchangeRateStored() public view returns (uint) {
        (MathError err, uint result) = exchangeRateStoredInternal();
        require(err == MathError.NO_ERROR, "exchangeRateStored: exchangeRateStoredInternal failed");
        return result;
    }

    /**
     * @notice Calculates the exchange rate from the underlying to the CToken
     * @dev This function does not accrue interest before calculating the exchange rate
     * @return (error code, calculated exchange rate scaled by 1e18)
     */
    function exchangeRateStoredInternal() internal view returns (MathError, uint) {
        if (totalSupply == 0) {
            /*
             * If there are no tokens minted:
             *  exchangeRate = initialExchangeRate
             */
            return (MathError.NO_ERROR, initialExchangeRateMantissa);
        } else {
            /*
             * Otherwise:
             *  exchangeRate = (totalCash + totalBorrows - totalReserves) / totalSupply
             */
            uint totalCash = getCashPrior();
            uint cashPlusBorrowsMinusReserves;
            Exp memory exchangeRate;
            MathError mathErr;

            (mathErr, cashPlusBorrowsMinusReserves) = addThenSubUInt(totalCash, totalBorrows, totalReserves);
            if (mathErr != MathError.NO_ERROR) {
                return (mathErr, 0);
            }

            (mathErr, exchangeRate) = getExp(cashPlusBorrowsMinusReserves, totalSupply);
            if (mathErr != MathError.NO_ERROR) {
                return (mathErr, 0);
            }

            return (MathError.NO_ERROR, exchangeRate.mantissa);
        }
    }

    /**
     * @notice Get cash balance of this cToken in the underlying asset
     * @return The quantity of underlying asset owned by this contract
     */
    function getCash() external view returns (uint) {
        return getCashPrior();
    }

    struct AccrueInterestLocalVars {
        MathError mathErr;
        uint opaqueErr;
        uint borrowRateMantissa;
        uint currentBlockNumber;
        uint blockDelta;

        Exp simpleInterestFactor;

        uint interestAccumulated;
        uint totalBorrowsNew;
        uint totalReservesNew;
        uint borrowIndexNew;
    }

    /**
      * @notice Applies accrued interest to total borrows and reserves.
      * @dev This calculates interest accrued from the last checkpointed block
      *      up to the current block and writes new checkpoint to storage.
      */
    function accrueInterest() public returns (uint) {
        AccrueInterestLocalVars memory vars;

        /* Calculate the current borrow interest rate */
        (vars.opaqueErr, vars.borrowRateMantissa) = interestRateModel.getBorrowRate(getCashPrior(), totalBorrows, totalReserves);
        require(vars.borrowRateMantissa <= borrowRateMaxMantissa, "borrow rate is absurdly high");
        if (vars.opaqueErr != 0) {
            return failOpaque(Error.INTEREST_RATE_MODEL_ERROR, FailureInfo.ACCRUE_INTEREST_BORROW_RATE_CALCULATION_FAILED, vars.opaqueErr);
        }

        /* Remember the initial block number */
        vars.currentBlockNumber = getBlockNumber();

        /* Calculate the number of blocks elapsed since the last accrual */
        (vars.mathErr, vars.blockDelta) = subUInt(vars.currentBlockNumber, accrualBlockNumber);
        assert(vars.mathErr == MathError.NO_ERROR); // Block delta should always succeed and if it doesn't, blow up.

        /*
         * Calculate the interest accumulated into borrows and reserves and the new index:
         *  simpleInterestFactor = borrowRate * blockDelta
         *  interestAccumulated = simpleInterestFactor * totalBorrows
         *  totalBorrowsNew = interestAccumulated + totalBorrows
         *  totalReservesNew = interestAccumulated * reserveFactor + totalReserves
         *  borrowIndexNew = simpleInterestFactor * borrowIndex + borrowIndex
         */
        (vars.mathErr, vars.simpleInterestFactor) = mulScalar(Exp({mantissa: vars.borrowRateMantissa}), vars.blockDelta);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_SIMPLE_INTEREST_FACTOR_CALCULATION_FAILED, uint(vars.mathErr));
        }

        (vars.mathErr, vars.interestAccumulated) = mulScalarTruncate(vars.simpleInterestFactor, totalBorrows);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_ACCUMULATED_INTEREST_CALCULATION_FAILED, uint(vars.mathErr));
        }

        (vars.mathErr, vars.totalBorrowsNew) = addUInt(vars.interestAccumulated, totalBorrows);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_NEW_TOTAL_BORROWS_CALCULATION_FAILED, uint(vars.mathErr));
        }

        (vars.mathErr, vars.totalReservesNew) = mulScalarTruncateAddUInt(Exp({mantissa: reserveFactorMantissa}), vars.interestAccumulated, totalReserves);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_NEW_TOTAL_RESERVES_CALCULATION_FAILED, uint(vars.mathErr));
        }

        (vars.mathErr, vars.borrowIndexNew) = mulScalarTruncateAddUInt(vars.simpleInterestFactor, borrowIndex, borrowIndex);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_NEW_BORROW_INDEX_CALCULATION_FAILED, uint(vars.mathErr));
        }

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        /* We write the previously calculated values into storage */
        accrualBlockNumber = vars.currentBlockNumber;
        borrowIndex = vars.borrowIndexNew;
        totalBorrows = vars.totalBorrowsNew;
        totalReserves = vars.totalReservesNew;

        /* We emit an AccrueInterest event */
        emit AccrueInterest(vars.interestAccumulated, vars.borrowIndexNew, totalBorrows);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Sender supplies assets into the market and receives cTokens in exchange
     * @dev Accrues interest whether or not the operation succeeds, unless reverted
     * @param mintAmount The amount of the underlying asset to supply
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function mintInternal(uint mintAmount) internal nonReentrant returns (uint) {
        uint error = accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
            return fail(Error(error), FailureInfo.MINT_ACCRUE_INTEREST_FAILED);
        }
        // mintFresh emits the actual Mint event if successful and logs on errors, so we don't need to
        return mintFresh(msg.sender, mintAmount);
    }

    struct MintLocalVars {
        Error err;
        MathError mathErr;
        uint exchangeRateMantissa;
        uint mintTokens;
        uint totalSupplyNew;
        uint accountTokensNew;
    }

    /**
     * @notice User supplies assets into the market and receives cTokens in exchange
     * @dev Assumes interest has already been accrued up to the current block
     * @param minter The address of the account which is supplying the assets
     * @param mintAmount The amount of the underlying asset to supply
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function mintFresh(address minter, uint mintAmount) internal returns (uint) {
        /* Fail if mint not allowed */
        uint allowed = comptroller.mintAllowed(address(this), minter, mintAmount);
        if (allowed != 0) {
            return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.MINT_COMPTROLLER_REJECTION, allowed);
        }

        /* Verify market's block number equals current block number */
        if (accrualBlockNumber != getBlockNumber()) {
            return fail(Error.MARKET_NOT_FRESH, FailureInfo.MINT_FRESHNESS_CHECK);
        }

        MintLocalVars memory vars;

        /* Fail if checkTransferIn fails */
        vars.err = checkTransferIn(minter, mintAmount);
        if (vars.err != Error.NO_ERROR) {
            return fail(vars.err, FailureInfo.MINT_TRANSFER_IN_NOT_POSSIBLE);
        }

        /*
         * We get the current exchange rate and calculate the number of cTokens to be minted:
         *  mintTokens = mintAmount / exchangeRate
         */
        (vars.mathErr, vars.exchangeRateMantissa) = exchangeRateStoredInternal();
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.MINT_EXCHANGE_RATE_READ_FAILED, uint(vars.mathErr));
        }

        (vars.mathErr, vars.mintTokens) = divScalarByExpTruncate(mintAmount, Exp({mantissa: vars.exchangeRateMantissa}));
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.MINT_EXCHANGE_CALCULATION_FAILED, uint(vars.mathErr));
        }

        /*
         * We calculate the new total supply of cTokens and minter token balance, checking for overflow:
         *  totalSupplyNew = totalSupply + mintTokens
         *  accountTokensNew = accountTokens[minter] + mintTokens
         */
        (vars.mathErr, vars.totalSupplyNew) = addUInt(totalSupply, vars.mintTokens);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.MINT_NEW_TOTAL_SUPPLY_CALCULATION_FAILED, uint(vars.mathErr));
        }

        (vars.mathErr, vars.accountTokensNew) = addUInt(accountTokens[minter], vars.mintTokens);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.MINT_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
        }

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        /*
         * We call doTransferIn for the minter and the mintAmount
         *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
         *  On success, the cToken holds an additional mintAmount of cash.
         *  If doTransferIn fails despite the fact we checked pre-conditions,
         *   we revert because we can't be sure if side effects occurred.
         */
        vars.err = doTransferIn(minter, mintAmount);
        if (vars.err != Error.NO_ERROR) {
            return fail(vars.err, FailureInfo.MINT_TRANSFER_IN_FAILED);
        }

        /* We write previously calculated values into storage */
        totalSupply = vars.totalSupplyNew;
        accountTokens[minter] = vars.accountTokensNew;

        /* We emit a Mint event, and a Transfer event */
        emit Mint(minter, mintAmount, vars.mintTokens);
        emit Transfer(address(this), minter, vars.mintTokens);

        /* We call the defense hook */
        comptroller.mintVerify(address(this), minter, mintAmount, vars.mintTokens);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Sender redeems cTokens in exchange for the underlying asset
     * @dev Accrues interest whether or not the operation succeeds, unless reverted
     * @param redeemTokens The number of cTokens to redeem into underlying
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function redeemInternal(uint redeemTokens) internal nonReentrant returns (uint) {
        uint error = accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted redeem failed
            return fail(Error(error), FailureInfo.REDEEM_ACCRUE_INTEREST_FAILED);
        }
        // redeemFresh emits redeem-specific logs on errors, so we don't need to
        return redeemFresh(msg.sender, redeemTokens, 0);
    }

    /**
     * @notice Sender redeems cTokens in exchange for a specified amount of underlying asset
     * @dev Accrues interest whether or not the operation succeeds, unless reverted
     * @param redeemAmount The amount of underlying to redeem
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function redeemUnderlyingInternal(uint redeemAmount) internal nonReentrant returns (uint) {
        uint error = accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted redeem failed
            return fail(Error(error), FailureInfo.REDEEM_ACCRUE_INTEREST_FAILED);
        }
        // redeemFresh emits redeem-specific logs on errors, so we don't need to
        return redeemFresh(msg.sender, 0, redeemAmount);
    }

    struct RedeemLocalVars {
        Error err;
        MathError mathErr;
        uint exchangeRateMantissa;
        uint redeemTokens;
        uint redeemAmount;
        uint totalSupplyNew;
        uint accountTokensNew;
    }

    /**
     * @notice User redeems cTokens in exchange for the underlying asset
     * @dev Assumes interest has already been accrued up to the current block
     * @param redeemer The address of the account which is redeeming the tokens
     * @param redeemTokensIn The number of cTokens to redeem into underlying (only one of redeemTokensIn or redeemAmountIn may be zero)
     * @param redeemAmountIn The number of cTokens to redeem into underlying (only one of redeemTokensIn or redeemAmountIn may be zero)
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function redeemFresh(address payable redeemer, uint redeemTokensIn, uint redeemAmountIn) internal returns (uint) {
        require(redeemTokensIn == 0 || redeemAmountIn == 0, "one of redeemTokensIn or redeemAmountIn must be zero");

        RedeemLocalVars memory vars;

        /* exchangeRate = invoke Exchange Rate Stored() */
        (vars.mathErr, vars.exchangeRateMantissa) = exchangeRateStoredInternal();
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_EXCHANGE_RATE_READ_FAILED, uint(vars.mathErr));
        }

        /* If redeemTokensIn > 0: */
        if (redeemTokensIn > 0) {
            /*
             * We calculate the exchange rate and the amount of underlying to be redeemed:
             *  redeemTokens = redeemTokensIn
             *  redeemAmount = redeemTokensIn x exchangeRateCurrent
             */
            vars.redeemTokens = redeemTokensIn;

            (vars.mathErr, vars.redeemAmount) = mulScalarTruncate(Exp({mantissa: vars.exchangeRateMantissa}), redeemTokensIn);
            if (vars.mathErr != MathError.NO_ERROR) {
                return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_EXCHANGE_TOKENS_CALCULATION_FAILED, uint(vars.mathErr));
            }
        } else {
            /*
             * We get the current exchange rate and calculate the amount to be redeemed:
             *  redeemTokens = redeemAmountIn / exchangeRate
             *  redeemAmount = redeemAmountIn
             */

            (vars.mathErr, vars.redeemTokens) = divScalarByExpTruncate(redeemAmountIn, Exp({mantissa: vars.exchangeRateMantissa}));
            if (vars.mathErr != MathError.NO_ERROR) {
                return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_EXCHANGE_AMOUNT_CALCULATION_FAILED, uint(vars.mathErr));
            }

            vars.redeemAmount = redeemAmountIn;
        }

        /* Fail if redeem not allowed */
        uint allowed = comptroller.redeemAllowed(address(this), redeemer, vars.redeemTokens);
        if (allowed != 0) {
            return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.REDEEM_COMPTROLLER_REJECTION, allowed);
        }

        /* Verify market's block number equals current block number */
        if (accrualBlockNumber != getBlockNumber()) {
            return fail(Error.MARKET_NOT_FRESH, FailureInfo.REDEEM_FRESHNESS_CHECK);
        }

        /*
         * We calculate the new total supply and redeemer balance, checking for underflow:
         *  totalSupplyNew = totalSupply - redeemTokens
         *  accountTokensNew = accountTokens[redeemer] - redeemTokens
         */
        (vars.mathErr, vars.totalSupplyNew) = subUInt(totalSupply, vars.redeemTokens);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_NEW_TOTAL_SUPPLY_CALCULATION_FAILED, uint(vars.mathErr));
        }

        (vars.mathErr, vars.accountTokensNew) = subUInt(accountTokens[redeemer], vars.redeemTokens);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
        }

        /* Fail gracefully if protocol has insufficient cash */
        if (getCashPrior() < vars.redeemAmount) {
            return fail(Error.TOKEN_INSUFFICIENT_CASH, FailureInfo.REDEEM_TRANSFER_OUT_NOT_POSSIBLE);
        }

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        /*
         * We invoke doTransferOut for the redeemer and the redeemAmount.
         *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
         *  On success, the cToken has redeemAmount less of cash.
         *  If doTransferOut fails despite the fact we checked pre-conditions,
         *   we revert because we can't be sure if side effects occurred.
         */
        vars.err = doTransferOut(redeemer, vars.redeemAmount);
        require(vars.err == Error.NO_ERROR, "redeem transfer out failed");

        /* We write previously calculated values into storage */
        totalSupply = vars.totalSupplyNew;
        accountTokens[redeemer] = vars.accountTokensNew;

        /* We emit a Transfer event, and a Redeem event */
        emit Transfer(redeemer, address(this), vars.redeemTokens);
        emit Redeem(redeemer, vars.redeemAmount, vars.redeemTokens);

        /* We call the defense hook */
        comptroller.redeemVerify(address(this), redeemer, vars.redeemAmount, vars.redeemTokens);

        return uint(Error.NO_ERROR);
    }

    /**
      * @notice Sender borrows assets from the protocol to their own address
      * @param borrowAmount The amount of the underlying asset to borrow
      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
      */
    function borrowInternal(uint borrowAmount) internal nonReentrant returns (uint) {
        uint error = accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
            return fail(Error(error), FailureInfo.BORROW_ACCRUE_INTEREST_FAILED);
        }
        // borrowFresh emits borrow-specific logs on errors, so we don't need to
        return borrowFresh(msg.sender, borrowAmount);
    }

    struct BorrowLocalVars {
        Error err;
        MathError mathErr;
        uint accountBorrows;
        uint accountBorrowsNew;
        uint totalBorrowsNew;
    }

    /**
      * @notice Users borrow assets from the protocol to their own address
      * @param borrowAmount The amount of the underlying asset to borrow
      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
      */
    function borrowFresh(address payable borrower, uint borrowAmount) internal returns (uint) {
        /* Fail if borrow not allowed */
        uint allowed = comptroller.borrowAllowed(address(this), borrower, borrowAmount);
        if (allowed != 0) {
            return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.BORROW_COMPTROLLER_REJECTION, allowed);
        }

        /* Verify market's block number equals current block number */
        if (accrualBlockNumber != getBlockNumber()) {
            return fail(Error.MARKET_NOT_FRESH, FailureInfo.BORROW_FRESHNESS_CHECK);
        }

        /* Fail gracefully if protocol has insufficient underlying cash */
        if (getCashPrior() < borrowAmount) {
            return fail(Error.TOKEN_INSUFFICIENT_CASH, FailureInfo.BORROW_CASH_NOT_AVAILABLE);
        }

        BorrowLocalVars memory vars;

        /*
         * We calculate the new borrower and total borrow balances, failing on overflow:
         *  accountBorrowsNew = accountBorrows + borrowAmount
         *  totalBorrowsNew = totalBorrows + borrowAmount
         */
        (vars.mathErr, vars.accountBorrows) = borrowBalanceStoredInternal(borrower);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
        }

        (vars.mathErr, vars.accountBorrowsNew) = addUInt(vars.accountBorrows, borrowAmount);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
        }

        (vars.mathErr, vars.totalBorrowsNew) = addUInt(totalBorrows, borrowAmount);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
        }

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        /*
         * We invoke doTransferOut for the borrower and the borrowAmount.
         *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
         *  On success, the cToken borrowAmount less of cash.
         *  If doTransferOut fails despite the fact we checked pre-conditions,
         *   we revert because we can't be sure if side effects occurred.
         */
        vars.err = doTransferOut(borrower, borrowAmount);
        require(vars.err == Error.NO_ERROR, "borrow transfer out failed");

        /* We write the previously calculated values into storage */
        accountBorrows[borrower].principal = vars.accountBorrowsNew;
        accountBorrows[borrower].interestIndex = borrowIndex;
        totalBorrows = vars.totalBorrowsNew;

        /* We emit a Borrow event */
        emit Borrow(borrower, borrowAmount, vars.accountBorrowsNew, vars.totalBorrowsNew);

        /* We call the defense hook */
        comptroller.borrowVerify(address(this), borrower, borrowAmount);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Sender repays their own borrow
     * @param repayAmount The amount to repay
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function repayBorrowInternal(uint repayAmount) internal nonReentrant returns (uint) {
        uint error = accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
            return fail(Error(error), FailureInfo.REPAY_BORROW_ACCRUE_INTEREST_FAILED);
        }
        // repayBorrowFresh emits repay-borrow-specific logs on errors, so we don't need to
        return repayBorrowFresh(msg.sender, msg.sender, repayAmount);
    }

    /**
     * @notice Sender repays a borrow belonging to borrower
     * @param borrower the account with the debt being payed off
     * @param repayAmount The amount to repay
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function repayBorrowBehalfInternal(address borrower, uint repayAmount) internal nonReentrant returns (uint) {
        uint error = accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
            return fail(Error(error), FailureInfo.REPAY_BEHALF_ACCRUE_INTEREST_FAILED);
        }
        // repayBorrowFresh emits repay-borrow-specific logs on errors, so we don't need to
        return repayBorrowFresh(msg.sender, borrower, repayAmount);
    }

    struct RepayBorrowLocalVars {
        Error err;
        MathError mathErr;
        uint repayAmount;
        uint borrowerIndex;
        uint accountBorrows;
        uint accountBorrowsNew;
        uint totalBorrowsNew;
    }

    /**
     * @notice Borrows are repaid by another user (possibly the borrower).
     * @param payer the account paying off the borrow
     * @param borrower the account with the debt being payed off
     * @param repayAmount the amount of undelrying tokens being returned
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function repayBorrowFresh(address payer, address borrower, uint repayAmount) internal returns (uint) {
        /* Fail if repayBorrow not allowed */
        uint allowed = comptroller.repayBorrowAllowed(address(this), payer, borrower, repayAmount);
        if (allowed != 0) {
            return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.REPAY_BORROW_COMPTROLLER_REJECTION, allowed);
        }

        /* Verify market's block number equals current block number */
        if (accrualBlockNumber != getBlockNumber()) {
            return fail(Error.MARKET_NOT_FRESH, FailureInfo.REPAY_BORROW_FRESHNESS_CHECK);
        }

        RepayBorrowLocalVars memory vars;

        /* We remember the original borrowerIndex for verification purposes */
        vars.borrowerIndex = accountBorrows[borrower].interestIndex;

        /* We fetch the amount the borrower owes, with accumulated interest */
        (vars.mathErr, vars.accountBorrows) = borrowBalanceStoredInternal(borrower);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.REPAY_BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
        }

        /* If repayAmount == -1, repayAmount = accountBorrows */
        if (repayAmount == uint(-1)) {
            vars.repayAmount = vars.accountBorrows;
        } else {
            vars.repayAmount = repayAmount;
        }

        /* Fail if checkTransferIn fails */
        vars.err = checkTransferIn(payer, vars.repayAmount);
        if (vars.err != Error.NO_ERROR) {
            return fail(vars.err, FailureInfo.REPAY_BORROW_TRANSFER_IN_NOT_POSSIBLE);
        }

        /*
         * We calculate the new borrower and total borrow balances, failing on underflow:
         *  accountBorrowsNew = accountBorrows - repayAmount
         *  totalBorrowsNew = totalBorrows - repayAmount
         */
        (vars.mathErr, vars.accountBorrowsNew) = subUInt(vars.accountBorrows, vars.repayAmount);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.REPAY_BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
        }

        (vars.mathErr, vars.totalBorrowsNew) = subUInt(totalBorrows, vars.repayAmount);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.REPAY_BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
        }

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        /*
         * We call doTransferIn for the payer and the repayAmount
         *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
         *  On success, the cToken holds an additional repayAmount of cash.
         *  If doTransferIn fails despite the fact we checked pre-conditions,
         *   we revert because we can't be sure if side effects occurred.
         */
        vars.err = doTransferIn(payer, vars.repayAmount);
        require(vars.err == Error.NO_ERROR, "repay borrow transfer in failed");

        /* We write the previously calculated values into storage */
        accountBorrows[borrower].principal = vars.accountBorrowsNew;
        accountBorrows[borrower].interestIndex = borrowIndex;
        totalBorrows = vars.totalBorrowsNew;

        /* We emit a RepayBorrow event */
        emit RepayBorrow(payer, borrower, vars.repayAmount, vars.accountBorrowsNew, vars.totalBorrowsNew);

        /* We call the defense hook */
        comptroller.repayBorrowVerify(address(this), payer, borrower, vars.repayAmount, vars.borrowerIndex);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice The sender liquidates the borrowers collateral.
     *  The collateral seized is transferred to the liquidator.
     * @param borrower The borrower of this cToken to be liquidated
     * @param cTokenCollateral The market in which to seize collateral from the borrower
     * @param repayAmount The amount of the underlying borrowed asset to repay
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function liquidateBorrowInternal(address borrower, uint repayAmount, CToken cTokenCollateral) internal nonReentrant returns (uint) {
        uint error = accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted liquidation failed
            return fail(Error(error), FailureInfo.LIQUIDATE_ACCRUE_BORROW_INTEREST_FAILED);
        }

        error = cTokenCollateral.accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted liquidation failed
            return fail(Error(error), FailureInfo.LIQUIDATE_ACCRUE_COLLATERAL_INTEREST_FAILED);
        }

        // liquidateBorrowFresh emits borrow-specific logs on errors, so we don't need to
        return liquidateBorrowFresh(msg.sender, borrower, repayAmount, cTokenCollateral);
    }

    /**
     * @notice The liquidator liquidates the borrowers collateral.
     *  The collateral seized is transferred to the liquidator.
     * @param borrower The borrower of this cToken to be liquidated
     * @param liquidator The address repaying the borrow and seizing collateral
     * @param cTokenCollateral The market in which to seize collateral from the borrower
     * @param repayAmount The amount of the underlying borrowed asset to repay
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function liquidateBorrowFresh(address liquidator, address borrower, uint repayAmount, CToken cTokenCollateral) internal returns (uint) {
        /* Fail if liquidate not allowed */
        uint allowed = comptroller.liquidateBorrowAllowed(address(this), address(cTokenCollateral), liquidator, borrower, repayAmount);
        if (allowed != 0) {
            return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.LIQUIDATE_COMPTROLLER_REJECTION, allowed);
        }

        /* Verify market's block number equals current block number */
        if (accrualBlockNumber != getBlockNumber()) {
            return fail(Error.MARKET_NOT_FRESH, FailureInfo.LIQUIDATE_FRESHNESS_CHECK);
        }

        /* Verify cTokenCollateral market's block number equals current block number */
        if (cTokenCollateral.accrualBlockNumber() != getBlockNumber()) {
            return fail(Error.MARKET_NOT_FRESH, FailureInfo.LIQUIDATE_COLLATERAL_FRESHNESS_CHECK);
        }

        /* Fail if borrower = liquidator */
        if (borrower == liquidator) {
            return fail(Error.INVALID_ACCOUNT_PAIR, FailureInfo.LIQUIDATE_LIQUIDATOR_IS_BORROWER);
        }

        /* Fail if repayAmount = 0 */
        if (repayAmount == 0) {
            return fail(Error.INVALID_CLOSE_AMOUNT_REQUESTED, FailureInfo.LIQUIDATE_CLOSE_AMOUNT_IS_ZERO);
        }

        /* Fail if repayAmount = -1 */
        if (repayAmount == uint(-1)) {
            return fail(Error.INVALID_CLOSE_AMOUNT_REQUESTED, FailureInfo.LIQUIDATE_CLOSE_AMOUNT_IS_UINT_MAX);
        }

        /* We calculate the number of collateral tokens that will be seized */
        (uint amountSeizeError, uint seizeTokens) = comptroller.liquidateCalculateSeizeTokens(address(this), address(cTokenCollateral), repayAmount);
        if (amountSeizeError != 0) {
            return failOpaque(Error.COMPTROLLER_CALCULATION_ERROR, FailureInfo.LIQUIDATE_COMPTROLLER_CALCULATE_AMOUNT_SEIZE_FAILED, amountSeizeError);
        }

        /* Fail if seizeTokens > borrower collateral token balance */
        if (seizeTokens > cTokenCollateral.balanceOf(borrower)) {
            return fail(Error.TOKEN_INSUFFICIENT_BALANCE, FailureInfo.LIQUIDATE_SEIZE_TOO_MUCH);
        }

        /* Fail if repayBorrow fails */
        uint repayBorrowError = repayBorrowFresh(liquidator, borrower, repayAmount);
        if (repayBorrowError != uint(Error.NO_ERROR)) {
            return fail(Error(repayBorrowError), FailureInfo.LIQUIDATE_REPAY_BORROW_FRESH_FAILED);
        }

        /* Revert if seize tokens fails (since we cannot be sure of side effects) */
        uint seizeError = cTokenCollateral.seize(liquidator, borrower, seizeTokens);
        require(seizeError == uint(Error.NO_ERROR), "token seizure failed");

        /* We emit a LiquidateBorrow event */
        emit LiquidateBorrow(liquidator, borrower, repayAmount, address(cTokenCollateral), seizeTokens);

        /* We call the defense hook */
        comptroller.liquidateBorrowVerify(address(this), address(cTokenCollateral), liquidator, borrower, repayAmount, seizeTokens);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Transfers collateral tokens (this market) to the liquidator.
     * @dev Will fail unless called by another cToken during the process of liquidation.
     *  Its absolutely critical to use msg.sender as the borrowed cToken and not a parameter.
     * @param liquidator The account receiving seized collateral
     * @param borrower The account having collateral seized
     * @param seizeTokens The number of cTokens to seize
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function seize(address liquidator, address borrower, uint seizeTokens) external nonReentrant returns (uint) {
        /* Fail if seize not allowed */
        uint allowed = comptroller.seizeAllowed(address(this), msg.sender, liquidator, borrower, seizeTokens);
        if (allowed != 0) {
            return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.LIQUIDATE_SEIZE_COMPTROLLER_REJECTION, allowed);
        }

        /* Fail if borrower = liquidator */
        if (borrower == liquidator) {
            return fail(Error.INVALID_ACCOUNT_PAIR, FailureInfo.LIQUIDATE_SEIZE_LIQUIDATOR_IS_BORROWER);
        }

        MathError mathErr;
        uint borrowerTokensNew;
        uint liquidatorTokensNew;

        /*
         * We calculate the new borrower and liquidator token balances, failing on underflow/overflow:
         *  borrowerTokensNew = accountTokens[borrower] - seizeTokens
         *  liquidatorTokensNew = accountTokens[liquidator] + seizeTokens
         */
        (mathErr, borrowerTokensNew) = subUInt(accountTokens[borrower], seizeTokens);
        if (mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.LIQUIDATE_SEIZE_BALANCE_DECREMENT_FAILED, uint(mathErr));
        }

        (mathErr, liquidatorTokensNew) = addUInt(accountTokens[liquidator], seizeTokens);
        if (mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.LIQUIDATE_SEIZE_BALANCE_INCREMENT_FAILED, uint(mathErr));
        }

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        /* We write the previously calculated values into storage */
        accountTokens[borrower] = borrowerTokensNew;
        accountTokens[liquidator] = liquidatorTokensNew;

        /* Emit a Transfer event */
        emit Transfer(borrower, liquidator, seizeTokens);

        /* We call the defense hook */
        comptroller.seizeVerify(address(this), msg.sender, liquidator, borrower, seizeTokens);

        return uint(Error.NO_ERROR);
    }


    /*** Admin Functions ***/

    /**
      * @notice Begins transfer of admin rights. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
      * @dev Admin function to begin change of admin. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
      * @param newPendingAdmin New pending admin.
      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
      *
      * TODO: Should we add a second arg to verify, like a checksum of `newAdmin` address?
      */
    function _setPendingAdmin(address payable newPendingAdmin) external returns (uint) {
        // Check caller = admin
        if (msg.sender != admin) {
            return fail(Error.UNAUTHORIZED, FailureInfo.SET_PENDING_ADMIN_OWNER_CHECK);
        }

        // Save current value, if any, for inclusion in log
        address oldPendingAdmin = pendingAdmin;

        // Store pendingAdmin with value newPendingAdmin
        pendingAdmin = newPendingAdmin;

        // Emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin)
        emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin);

        return uint(Error.NO_ERROR);
    }

    /**
      * @notice Accepts transfer of admin rights. msg.sender must be pendingAdmin
      * @dev Admin function for pending admin to accept role and update admin
      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
      */
    function _acceptAdmin() external returns (uint) {
        // Check caller is pendingAdmin and pendingAdmin ≠ address(0)
        if (msg.sender != pendingAdmin || msg.sender == address(0)) {
            return fail(Error.UNAUTHORIZED, FailureInfo.ACCEPT_ADMIN_PENDING_ADMIN_CHECK);
        }

        // Save current values for inclusion in log
        address oldAdmin = admin;
        address oldPendingAdmin = pendingAdmin;

        // Store admin with value pendingAdmin
        admin = pendingAdmin;

        // Clear the pending value
        pendingAdmin = address(0);

        emit NewAdmin(oldAdmin, admin);
        emit NewPendingAdmin(oldPendingAdmin, pendingAdmin);

        return uint(Error.NO_ERROR);
    }

    /**
      * @notice Sets a new comptroller for the market
      * @dev Admin function to set a new comptroller
      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
      */
    function _setComptroller(ComptrollerInterface newComptroller) public returns (uint) {
        // Check caller is admin
        if (msg.sender != admin) {
            return fail(Error.UNAUTHORIZED, FailureInfo.SET_COMPTROLLER_OWNER_CHECK);
        }

        ComptrollerInterface oldComptroller = comptroller;
        // Ensure invoke comptroller.isComptroller() returns true
        require(newComptroller.isComptroller(), "marker method returned false");

        // Set market's comptroller to newComptroller
        comptroller = newComptroller;

        // Emit NewComptroller(oldComptroller, newComptroller)
        emit NewComptroller(oldComptroller, newComptroller);

        return uint(Error.NO_ERROR);
    }

    /**
      * @notice accrues interest and sets a new reserve factor for the protocol using _setReserveFactorFresh
      * @dev Admin function to accrue interest and set a new reserve factor
      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
      */
    function _setReserveFactor(uint newReserveFactorMantissa) external nonReentrant returns (uint) {
        uint error = accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted reserve factor change failed.
            return fail(Error(error), FailureInfo.SET_RESERVE_FACTOR_ACCRUE_INTEREST_FAILED);
        }
        // _setReserveFactorFresh emits reserve-factor-specific logs on errors, so we don't need to.
        return _setReserveFactorFresh(newReserveFactorMantissa);
    }

    /**
      * @notice Sets a new reserve factor for the protocol (*requires fresh interest accrual)
      * @dev Admin function to set a new reserve factor
      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
      */
    function _setReserveFactorFresh(uint newReserveFactorMantissa) internal returns (uint) {
        // Check caller is admin
        if (msg.sender != admin) {
            return fail(Error.UNAUTHORIZED, FailureInfo.SET_RESERVE_FACTOR_ADMIN_CHECK);
        }

        // Verify market's block number equals current block number
        if (accrualBlockNumber != getBlockNumber()) {
            // TODO: static_assert + no error code?
            return fail(Error.MARKET_NOT_FRESH, FailureInfo.SET_RESERVE_FACTOR_FRESH_CHECK);
        }

        // Check newReserveFactor ≤ maxReserveFactor
        if (newReserveFactorMantissa > reserveFactorMaxMantissa) {
            return fail(Error.BAD_INPUT, FailureInfo.SET_RESERVE_FACTOR_BOUNDS_CHECK);
        }

        uint oldReserveFactorMantissa = reserveFactorMantissa;
        reserveFactorMantissa = newReserveFactorMantissa;

        emit NewReserveFactor(oldReserveFactorMantissa, newReserveFactorMantissa);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Accrues interest and reduces reserves by transferring to admin
     * @param reduceAmount Amount of reduction to reserves
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _reduceReserves(uint reduceAmount) external nonReentrant returns (uint) {
        uint error = accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted reduce reserves failed.
            return fail(Error(error), FailureInfo.REDUCE_RESERVES_ACCRUE_INTEREST_FAILED);
        }
        // _reduceReservesFresh emits reserve-reduction-specific logs on errors, so we don't need to.
        return _reduceReservesFresh(reduceAmount);
    }

    /**
     * @notice Reduces reserves by transferring to admin
     * @dev Requires fresh interest accrual
     * @param reduceAmount Amount of reduction to reserves
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _reduceReservesFresh(uint reduceAmount) internal returns (uint) {
        Error err;
        // totalReserves - reduceAmount
        uint totalReservesNew;

        // Check caller is admin
        if (msg.sender != admin) {
            return fail(Error.UNAUTHORIZED, FailureInfo.REDUCE_RESERVES_ADMIN_CHECK);
        }

        // We fail gracefully unless market's block number equals current block number
        if (accrualBlockNumber != getBlockNumber()) {
            // TODO: static_assert + no error code?
            return fail(Error.MARKET_NOT_FRESH, FailureInfo.REDUCE_RESERVES_FRESH_CHECK);
        }

        // Fail gracefully if protocol has insufficient underlying cash
        if (getCashPrior() < reduceAmount) {
            return fail(Error.TOKEN_INSUFFICIENT_CASH, FailureInfo.REDUCE_RESERVES_CASH_NOT_AVAILABLE);
        }

        // Check reduceAmount ≤ reserves[n] (totalReserves)
        // TODO: I'm following the spec literally here but I think we should we just use SafeMath instead and fail on an error (which would be underflow)
        if (reduceAmount > totalReserves) {
            return fail(Error.BAD_INPUT, FailureInfo.REDUCE_RESERVES_VALIDATION);
        }

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        totalReservesNew = totalReserves - reduceAmount;
        // We checked reduceAmount <= totalReserves above, so this should never revert.
        require(totalReservesNew <= totalReserves, "reduce reserves unexpected underflow");

        // Store reserves[n+1] = reserves[n] - reduceAmount
        totalReserves = totalReservesNew;

        // invoke doTransferOut(reduceAmount, admin)
        err = doTransferOut(admin, reduceAmount);
        // we revert on the failure of this command
        require(err == Error.NO_ERROR, "reduce reserves transfer out failed");

        emit ReservesReduced(admin, reduceAmount, totalReservesNew);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice accrues interest and updates the interest rate model using _setInterestRateModelFresh
     * @dev Admin function to accrue interest and update the interest rate model
     * @param newInterestRateModel the new interest rate model to use
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _setInterestRateModel(InterestRateModel newInterestRateModel) public returns (uint) {
        uint error = accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted change of interest rate model failed
            return fail(Error(error), FailureInfo.SET_INTEREST_RATE_MODEL_ACCRUE_INTEREST_FAILED);
        }
        // _setInterestRateModelFresh emits interest-rate-model-update-specific logs on errors, so we don't need to.
        return _setInterestRateModelFresh(newInterestRateModel);
    }

    /**
     * @notice updates the interest rate model (*requires fresh interest accrual)
     * @dev Admin function to update the interest rate model
     * @param newInterestRateModel the new interest rate model to use
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _setInterestRateModelFresh(InterestRateModel newInterestRateModel) internal returns (uint) {

        // Used to store old model for use in the event that is emitted on success
        InterestRateModel oldInterestRateModel;

        // Check caller is admin
        if (msg.sender != admin) {
            return fail(Error.UNAUTHORIZED, FailureInfo.SET_INTEREST_RATE_MODEL_OWNER_CHECK);
        }

        // We fail gracefully unless market's block number equals current block number
        if (accrualBlockNumber != getBlockNumber()) {
            // TODO: static_assert + no error code?
            return fail(Error.MARKET_NOT_FRESH, FailureInfo.SET_INTEREST_RATE_MODEL_FRESH_CHECK);
        }

        // Track the market's current interest rate model
        oldInterestRateModel = interestRateModel;

        // Ensure invoke newInterestRateModel.isInterestRateModel() returns true
        require(newInterestRateModel.isInterestRateModel(), "marker method returned false");

        // Set the interest rate model to newInterestRateModel
        interestRateModel = newInterestRateModel;

        // Emit NewMarketInterestRateModel(oldInterestRateModel, newInterestRateModel)
        emit NewMarketInterestRateModel(oldInterestRateModel, newInterestRateModel);

        return uint(Error.NO_ERROR);
    }

    /*** Safe Token ***/

    /**
     * @notice Gets balance of this contract in terms of the underlying
     * @dev This excludes the value of the current message, if any
     * @return The quantity of underlying owned by this contract
     */
    function getCashPrior() internal view returns (uint);

    /**
     * @dev Checks whether or not there is sufficient allowance for this contract to move amount from `from` and
     *      whether or not `from` has a balance of at least `amount`. Does NOT do a transfer.
     */
    function checkTransferIn(address from, uint amount) internal view returns (Error);

    /**
     * @dev Performs a transfer in, ideally returning an explanatory error code upon failure rather than reverting.
     *  If caller has not called `checkTransferIn`, this may revert due to insufficient balance or insufficient allowance.
     *  If caller has called `checkTransferIn` successfully, this should not revert in normal conditions.
     */
    function doTransferIn(address from, uint amount) internal returns (Error);

    /**
     * @dev Performs a transfer out, ideally returning an explanatory error code upon failure tather than reverting.
     *  If caller has not called checked protocol's balance, may revert due to insufficient cash held in the contract.
     *  If caller has checked protocol's balance, and verified it is >= amount, this should not revert in normal conditions.
     */
    function doTransferOut(address payable to, uint amount) internal returns (Error);
}

// File: contracts/CErc20.sol

pragma solidity ^0.5.8;


/**
 * @title Compound's CErc20 Contract
 * @notice CTokens which wrap an EIP-20 underlying
 * @author Compound
 */
contract CErc20 is CToken {

    /**
     * @notice Underlying asset for this CToken
     */
    address public underlying;

    /**
     * @notice Construct a new money market
     * @param underlying_ The address of the underlying asset
     * @param comptroller_ The address of the Comptroller
     * @param interestRateModel_ The address of the interest rate model
     * @param initialExchangeRateMantissa_ The initial exchange rate, scaled by 1e18
     * @param name_ ERC-20 name of this token
     * @param symbol_ ERC-20 symbol of this token
     * @param decimals_ ERC-20 decimal precision of this token
     */
    constructor(address underlying_,
                ComptrollerInterface comptroller_,
                InterestRateModel interestRateModel_,
                uint initialExchangeRateMantissa_,
                string memory name_,
                string memory symbol_,
                uint decimals_) public
    CToken(comptroller_, interestRateModel_, initialExchangeRateMantissa_, name_, symbol_, decimals_) {
        // Set underlying
        underlying = underlying_;
        EIP20Interface(underlying).totalSupply(); // Sanity check the underlying
    }

    /*** User Interface ***/

    /**
     * @notice Sender supplies assets into the market and receives cTokens in exchange
     * @dev Accrues interest whether or not the operation succeeds, unless reverted
     * @param mintAmount The amount of the underlying asset to supply
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function mint(uint mintAmount) external returns (uint) {
        return mintInternal(mintAmount);
    }

    /**
     * @notice Sender redeems cTokens in exchange for the underlying asset
     * @dev Accrues interest whether or not the operation succeeds, unless reverted
     * @param redeemTokens The number of cTokens to redeem into underlying
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function redeem(uint redeemTokens) external returns (uint) {
        return redeemInternal(redeemTokens);
    }

    /**
     * @notice Sender redeems cTokens in exchange for a specified amount of underlying asset
     * @dev Accrues interest whether or not the operation succeeds, unless reverted
     * @param redeemAmount The amount of underlying to redeem
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function redeemUnderlying(uint redeemAmount) external returns (uint) {
        return redeemUnderlyingInternal(redeemAmount);
    }

    /**
      * @notice Sender borrows assets from the protocol to their own address
      * @param borrowAmount The amount of the underlying asset to borrow
      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
      */
    function borrow(uint borrowAmount) external returns (uint) {
        return borrowInternal(borrowAmount);
    }

    /**
     * @notice Sender repays their own borrow
     * @param repayAmount The amount to repay
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function repayBorrow(uint repayAmount) external returns (uint) {
        return repayBorrowInternal(repayAmount);
    }

    /**
     * @notice Sender repays a borrow belonging to borrower
     * @param borrower the account with the debt being payed off
     * @param repayAmount The amount to repay
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function repayBorrowBehalf(address borrower, uint repayAmount) external returns (uint) {
        return repayBorrowBehalfInternal(borrower, repayAmount);
    }

    /**
     * @notice The sender liquidates the borrowers collateral.
     *  The collateral seized is transferred to the liquidator.
     * @param borrower The borrower of this cToken to be liquidated
     * @param cTokenCollateral The market in which to seize collateral from the borrower
     * @param repayAmount The amount of the underlying borrowed asset to repay
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function liquidateBorrow(address borrower, uint repayAmount, CToken cTokenCollateral) external returns (uint) {
        return liquidateBorrowInternal(borrower, repayAmount, cTokenCollateral);
    }

    /*** Safe Token ***/

    /**
     * @notice Gets balance of this contract in terms of the underlying
     * @dev This excludes the value of the current message, if any
     * @return The quantity of underlying tokens owned by this contract
     */
    function getCashPrior() internal view returns (uint) {
        EIP20Interface token = EIP20Interface(underlying);
        return token.balanceOf(address(this));
    }

    /**
     * @dev Checks whether or not there is sufficient allowance for this contract to move amount from `from` and
     *      whether or not `from` has a balance of at least `amount`. Does NOT do a transfer.
     */
    function checkTransferIn(address from, uint amount) internal view returns (Error) {
        EIP20Interface token = EIP20Interface(underlying);

        if (token.allowance(from, address(this)) < amount) {
            return Error.TOKEN_INSUFFICIENT_ALLOWANCE;
        }

        if (token.balanceOf(from) < amount) {
            return Error.TOKEN_INSUFFICIENT_BALANCE;
        }

        return Error.NO_ERROR;
    }

    /**
     * @dev Similar to EIP20 transfer, except it handles a False result from `transferFrom` and returns an explanatory
     *      error code rather than reverting.  If caller has not called `checkTransferIn`, this may revert due to
     *      insufficient balance or insufficient allowance. If caller has called `checkTransferIn` prior to this call,
     *      and it returned Error.NO_ERROR, this should not revert in normal conditions.
     *
     *      Note: This wrapper safely handles non-standard ERC-20 tokens that do not return a value.
     *            See here: https://medium.com/coinmonks/missing-return-value-bug-at-least-130-tokens-affected-d67bf08521ca
     */
    function doTransferIn(address from, uint amount) internal returns (Error) {
        EIP20NonStandardInterface token = EIP20NonStandardInterface(underlying);
        bool result;

        token.transferFrom(from, address(this), amount);

        // solium-disable-next-line security/no-inline-assembly
        assembly {
            switch returndatasize()
                case 0 {                      // This is a non-standard ERC-20
                    result := not(0)          // set result to true
                }
                case 32 {                     // This is a complaint ERC-20
                    returndatacopy(0, 0, 32)
                    result := mload(0)        // Set `result = returndata` of external call
                }
                default {                     // This is an excessively non-compliant ERC-20, revert.
                    revert(0, 0)
                }
        }

        if (!result) {
            return Error.TOKEN_TRANSFER_IN_FAILED;
        }

        return Error.NO_ERROR;
    }

    /**
     * @dev Similar to EIP20 transfer, except it handles a False result from `transfer` and returns an explanatory
     *      error code rather than reverting. If caller has not called checked protocol's balance, this may revert due to
     *      insufficient cash held in this contract. If caller has checked protocol's balance prior to this call, and verified
     *      it is >= amount, this should not revert in normal conditions.
     *
     *      Note: This wrapper safely handles non-standard ERC-20 tokens that do not return a value.
     *            See here: https://medium.com/coinmonks/missing-return-value-bug-at-least-130-tokens-affected-d67bf08521ca
     */
    function doTransferOut(address payable to, uint amount) internal returns (Error) {
        EIP20NonStandardInterface token = EIP20NonStandardInterface(underlying);
        bool result;

        token.transfer(to, amount);

        // solium-disable-next-line security/no-inline-assembly
        assembly {
            switch returndatasize()
                case 0 {                      // This is a non-standard ERC-20
                    result := not(0)          // set result to true
                }
                case 32 {                     // This is a complaint ERC-20
                    returndatacopy(0, 0, 32)
                    result := mload(0)        // Set `result = returndata` of external call
                }
                default {                     // This is an excessively non-compliant ERC-20, revert.
                    revert(0, 0)
                }
        }

        if (!result) {
            return Error.TOKEN_TRANSFER_OUT_FAILED;
        }

        return Error.NO_ERROR;
    }
}

// File: contracts/ErrorReporter.sol

pragma solidity ^0.5.8;

contract ComptrollerErrorReporter {
    enum Error {
        NO_ERROR,
        UNAUTHORIZED,
        COMPTROLLER_MISMATCH,
        INSUFFICIENT_SHORTFALL,
        INSUFFICIENT_LIQUIDITY,
        INVALID_CLOSE_FACTOR,
        INVALID_COLLATERAL_FACTOR,
        INVALID_LIQUIDATION_INCENTIVE,
        MARKET_NOT_ENTERED,
        MARKET_NOT_LISTED,
        MARKET_ALREADY_LISTED,
        MATH_ERROR,
        NONZERO_BORROW_BALANCE,
        PRICE_ERROR,
        REJECTION,
        SNAPSHOT_ERROR,
        TOO_MANY_ASSETS,
        TOO_MUCH_REPAY
    }

    enum FailureInfo {
        ACCEPT_ADMIN_PENDING_ADMIN_CHECK,
        ACCEPT_PENDING_IMPLEMENTATION_ADDRESS_CHECK,
        EXIT_MARKET_BALANCE_OWED,
        EXIT_MARKET_REJECTION,
        SET_CLOSE_FACTOR_OWNER_CHECK,
        SET_CLOSE_FACTOR_VALIDATION,
        SET_COLLATERAL_FACTOR_OWNER_CHECK,
        SET_COLLATERAL_FACTOR_NO_EXISTS,
        SET_COLLATERAL_FACTOR_VALIDATION,
        SET_COLLATERAL_FACTOR_WITHOUT_PRICE,
        SET_IMPLEMENTATION_OWNER_CHECK,
        SET_LIQUIDATION_INCENTIVE_OWNER_CHECK,
        SET_LIQUIDATION_INCENTIVE_VALIDATION,
        SET_MAX_ASSETS_OWNER_CHECK,
        SET_PENDING_ADMIN_OWNER_CHECK,
        SET_PENDING_IMPLEMENTATION_OWNER_CHECK,
        SET_PRICE_ORACLE_OWNER_CHECK,
        SUPPORT_MARKET_EXISTS,
        SUPPORT_MARKET_OWNER_CHECK,
        ZUNUSED
    }

    /**
      * @dev `error` corresponds to enum Error; `info` corresponds to enum FailureInfo, and `detail` is an arbitrary
      * contract-specific code that enables us to report opaque error codes from upgradeable contracts.
      **/
    event Failure(uint error, uint info, uint detail);

    /**
      * @dev use this when reporting a known error from the money market or a non-upgradeable collaborator
      */
    function fail(Error err, FailureInfo info) internal returns (uint) {
        emit Failure(uint(err), uint(info), 0);

        return uint(err);
    }

    /**
      * @dev use this when reporting an opaque error from an upgradeable collaborator contract
      */
    function failOpaque(Error err, FailureInfo info, uint opaqueError) internal returns (uint) {
        emit Failure(uint(err), uint(info), opaqueError);

        return uint(err);
    }
}

contract TokenErrorReporter {
    enum Error {
        NO_ERROR,
        UNAUTHORIZED,
        BAD_INPUT,
        COMPTROLLER_REJECTION,
        COMPTROLLER_CALCULATION_ERROR,
        INTEREST_RATE_MODEL_ERROR,
        INVALID_ACCOUNT_PAIR,
        INVALID_CLOSE_AMOUNT_REQUESTED,
        INVALID_COLLATERAL_FACTOR,
        MATH_ERROR,
        MARKET_NOT_FRESH,
        MARKET_NOT_LISTED,
        TOKEN_INSUFFICIENT_ALLOWANCE,
        TOKEN_INSUFFICIENT_BALANCE,
        TOKEN_INSUFFICIENT_CASH,
        TOKEN_TRANSFER_IN_FAILED,
        TOKEN_TRANSFER_OUT_FAILED
    }

    /*
     * Note: FailureInfo (but not Error) is kept in alphabetical order
     *       This is because FailureInfo grows significantly faster, and
     *       the order of Error has some meaning, while the order of FailureInfo
     *       is entirely arbitrary.
     */
    enum FailureInfo {
        ACCEPT_ADMIN_PENDING_ADMIN_CHECK,
        ACCRUE_INTEREST_ACCUMULATED_INTEREST_CALCULATION_FAILED,
        ACCRUE_INTEREST_BORROW_RATE_CALCULATION_FAILED,
        ACCRUE_INTEREST_NEW_BORROW_INDEX_CALCULATION_FAILED,
        ACCRUE_INTEREST_NEW_TOTAL_BORROWS_CALCULATION_FAILED,
        ACCRUE_INTEREST_NEW_TOTAL_RESERVES_CALCULATION_FAILED,
        ACCRUE_INTEREST_SIMPLE_INTEREST_FACTOR_CALCULATION_FAILED,
        BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED,
        BORROW_ACCRUE_INTEREST_FAILED,
        BORROW_CASH_NOT_AVAILABLE,
        BORROW_FRESHNESS_CHECK,
        BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED,
        BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED,
        BORROW_MARKET_NOT_LISTED,
        BORROW_COMPTROLLER_REJECTION,
        LIQUIDATE_ACCRUE_BORROW_INTEREST_FAILED,
        LIQUIDATE_ACCRUE_COLLATERAL_INTEREST_FAILED,
        LIQUIDATE_COLLATERAL_FRESHNESS_CHECK,
        LIQUIDATE_COMPTROLLER_REJECTION,
        LIQUIDATE_COMPTROLLER_CALCULATE_AMOUNT_SEIZE_FAILED,
        LIQUIDATE_CLOSE_AMOUNT_IS_UINT_MAX,
        LIQUIDATE_CLOSE_AMOUNT_IS_ZERO,
        LIQUIDATE_FRESHNESS_CHECK,
        LIQUIDATE_LIQUIDATOR_IS_BORROWER,
        LIQUIDATE_REPAY_BORROW_FRESH_FAILED,
        LIQUIDATE_SEIZE_BALANCE_INCREMENT_FAILED,
        LIQUIDATE_SEIZE_BALANCE_DECREMENT_FAILED,
        LIQUIDATE_SEIZE_COMPTROLLER_REJECTION,
        LIQUIDATE_SEIZE_LIQUIDATOR_IS_BORROWER,
        LIQUIDATE_SEIZE_TOO_MUCH,
        MINT_ACCRUE_INTEREST_FAILED,
        MINT_COMPTROLLER_REJECTION,
        MINT_EXCHANGE_CALCULATION_FAILED,
        MINT_EXCHANGE_RATE_READ_FAILED,
        MINT_FRESHNESS_CHECK,
        MINT_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED,
        MINT_NEW_TOTAL_SUPPLY_CALCULATION_FAILED,
        MINT_TRANSFER_IN_FAILED,
        MINT_TRANSFER_IN_NOT_POSSIBLE,
        REDEEM_ACCRUE_INTEREST_FAILED,
        REDEEM_COMPTROLLER_REJECTION,
        REDEEM_EXCHANGE_TOKENS_CALCULATION_FAILED,
        REDEEM_EXCHANGE_AMOUNT_CALCULATION_FAILED,
        REDEEM_EXCHANGE_RATE_READ_FAILED,
        REDEEM_FRESHNESS_CHECK,
        REDEEM_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED,
        REDEEM_NEW_TOTAL_SUPPLY_CALCULATION_FAILED,
        REDEEM_TRANSFER_OUT_NOT_POSSIBLE,
        REDUCE_RESERVES_ACCRUE_INTEREST_FAILED,
        REDUCE_RESERVES_ADMIN_CHECK,
        REDUCE_RESERVES_CASH_NOT_AVAILABLE,
        REDUCE_RESERVES_FRESH_CHECK,
        REDUCE_RESERVES_VALIDATION,
        REPAY_BEHALF_ACCRUE_INTEREST_FAILED,
        REPAY_BORROW_ACCRUE_INTEREST_FAILED,
        REPAY_BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED,
        REPAY_BORROW_COMPTROLLER_REJECTION,
        REPAY_BORROW_FRESHNESS_CHECK,
        REPAY_BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED,
        REPAY_BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED,
        REPAY_BORROW_TRANSFER_IN_NOT_POSSIBLE,
        SET_COLLATERAL_FACTOR_OWNER_CHECK,
        SET_COLLATERAL_FACTOR_VALIDATION,
        SET_COMPTROLLER_OWNER_CHECK,
        SET_INTEREST_RATE_MODEL_ACCRUE_INTEREST_FAILED,
        SET_INTEREST_RATE_MODEL_FRESH_CHECK,
        SET_INTEREST_RATE_MODEL_OWNER_CHECK,
        SET_MAX_ASSETS_OWNER_CHECK,
        SET_ORACLE_MARKET_NOT_LISTED,
        SET_PENDING_ADMIN_OWNER_CHECK,
        SET_RESERVE_FACTOR_ACCRUE_INTEREST_FAILED,
        SET_RESERVE_FACTOR_ADMIN_CHECK,
        SET_RESERVE_FACTOR_FRESH_CHECK,
        SET_RESERVE_FACTOR_BOUNDS_CHECK,
        TRANSFER_COMPTROLLER_REJECTION,
        TRANSFER_NOT_ALLOWED,
        TRANSFER_NOT_ENOUGH,
        TRANSFER_TOO_MUCH
    }

    /**
      * @dev `error` corresponds to enum Error; `info` corresponds to enum FailureInfo, and `detail` is an arbitrary
      * contract-specific code that enables us to report opaque error codes from upgradeable contracts.
      **/
    event Failure(uint error, uint info, uint detail);

    /**
      * @dev use this when reporting a known error from the money market or a non-upgradeable collaborator
      */
    function fail(Error err, FailureInfo info) internal returns (uint) {
        emit Failure(uint(err), uint(info), 0);

        return uint(err);
    }

    /**
      * @dev use this when reporting an opaque error from an upgradeable collaborator contract
      */
    function failOpaque(Error err, FailureInfo info, uint opaqueError) internal returns (uint) {
        emit Failure(uint(err), uint(info), opaqueError);

        return uint(err);
    }
}

// File: contracts/ComptrollerInterface.sol

pragma solidity ^0.5.8;

interface ComptrollerInterface {
    /**
     * @notice Marker function used for light validation when updating the comptroller of a market
     * @dev Implementations should simply return true.
     * @return true
     */
    function isComptroller() external view returns (bool);

    /*** Assets You Are In ***/

    function enterMarkets(address[] calldata cTokens) external returns (uint[] memory);
    function exitMarket(address cToken) external returns (uint);

    /*** Policy Hooks ***/

    function mintAllowed(address cToken, address minter, uint mintAmount) external returns (uint);
    function mintVerify(address cToken, address minter, uint mintAmount, uint mintTokens) external;

    function redeemAllowed(address cToken, address redeemer, uint redeemTokens) external returns (uint);
    function redeemVerify(address cToken, address redeemer, uint redeemAmount, uint redeemTokens) external;

    function borrowAllowed(address cToken, address borrower, uint borrowAmount) external returns (uint);
    function borrowVerify(address cToken, address borrower, uint borrowAmount) external;

    function repayBorrowAllowed(
        address cToken,
        address payer,
        address borrower,
        uint repayAmount) external returns (uint);
    function repayBorrowVerify(
        address cToken,
        address payer,
        address borrower,
        uint repayAmount,
        uint borrowerIndex) external;

    function liquidateBorrowAllowed(
        address cTokenBorrowed,
        address cTokenCollateral,
        address liquidator,
        address borrower,
        uint repayAmount) external returns (uint);
    function liquidateBorrowVerify(
        address cTokenBorrowed,
        address cTokenCollateral,
        address liquidator,
        address borrower,
        uint repayAmount,
        uint seizeTokens) external;

    function seizeAllowed(
        address cTokenCollateral,
        address cTokenBorrowed,
        address liquidator,
        address borrower,
        uint seizeTokens) external returns (uint);
    function seizeVerify(
        address cTokenCollateral,
        address cTokenBorrowed,
        address liquidator,
        address borrower,
        uint seizeTokens) external;

    function transferAllowed(address cToken, address src, address dst, uint transferTokens) external returns (uint);
    function transferVerify(address cToken, address src, address dst, uint transferTokens) external;

    /*** Liquidity/Liquidation Calculations ***/

    function liquidateCalculateSeizeTokens(
        address cTokenBorrowed,
        address cTokenCollateral,
        uint repayAmount) external view returns (uint, uint);
}

// File: contracts/CarefulMath.sol

pragma solidity ^0.5.8;

/**
  * @title Careful Math
  * @author Compound
  * @notice Derived from OpenZeppelin's SafeMath library
  *         https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/contracts/math/SafeMath.sol
  */
contract CarefulMath {

    /**
     * @dev Possible error codes that we can return
     */
    enum MathError {
        NO_ERROR,
        DIVISION_BY_ZERO,
        INTEGER_OVERFLOW,
        INTEGER_UNDERFLOW
    }

    /**
    * @dev Multiplies two numbers, returns an error on overflow.
    */
    function mulUInt(uint a, uint b) internal pure returns (MathError, uint) {
        if (a == 0) {
            return (MathError.NO_ERROR, 0);
        }

        uint c = a * b;

        if (c / a != b) {
            return (MathError.INTEGER_OVERFLOW, 0);
        } else {
            return (MathError.NO_ERROR, c);
        }
    }

    /**
    * @dev Integer division of two numbers, truncating the quotient.
    */
    function divUInt(uint a, uint b) internal pure returns (MathError, uint) {
        if (b == 0) {
            return (MathError.DIVISION_BY_ZERO, 0);
        }

        return (MathError.NO_ERROR, a / b);
    }

    /**
    * @dev Subtracts two numbers, returns an error on overflow (i.e. if subtrahend is greater than minuend).
    */
    function subUInt(uint a, uint b) internal pure returns (MathError, uint) {
        if (b <= a) {
            return (MathError.NO_ERROR, a - b);
        } else {
            return (MathError.INTEGER_UNDERFLOW, 0);
        }
    }

    /**
    * @dev Adds two numbers, returns an error on overflow.
    */
    function addUInt(uint a, uint b) internal pure returns (MathError, uint) {
        uint c = a + b;

        if (c >= a) {
            return (MathError.NO_ERROR, c);
        } else {
            return (MathError.INTEGER_OVERFLOW, 0);
        }
    }

    /**
    * @dev add a and b and then subtract c
    */
    function addThenSubUInt(uint a, uint b, uint c) internal pure returns (MathError, uint) {
        (MathError err0, uint sum) = addUInt(a, b);

        if (err0 != MathError.NO_ERROR) {
            return (err0, 0);
        }

        return subUInt(sum, c);
    }
}

// File: contracts/Exponential.sol

pragma solidity ^0.5.8;


/**
 * @title Exponential module for storing fixed-decision decimals
 * @author Compound
 * @notice Exp is a struct which stores decimals with a fixed precision of 18 decimal places.
 *         Thus, if we wanted to store the 5.1, mantissa would store 5.1e18. That is:
 *         `Exp({mantissa: 5100000000000000000})`.
 */
contract Exponential is CarefulMath {
    uint constant expScale = 1e18;
    uint constant halfExpScale = expScale/2;
    uint constant mantissaOne = expScale;

    struct Exp {
        uint mantissa;
    }

    /**
     * @dev Creates an exponential from numerator and denominator values.
     *      Note: Returns an error if (`num` * 10e18) > MAX_INT,
     *            or if `denom` is zero.
     */
    function getExp(uint num, uint denom) pure internal returns (MathError, Exp memory) {
        (MathError err0, uint scaledNumerator) = mulUInt(num, expScale);
        if (err0 != MathError.NO_ERROR) {
            return (err0, Exp({mantissa: 0}));
        }

        (MathError err1, uint rational) = divUInt(scaledNumerator, denom);
        if (err1 != MathError.NO_ERROR) {
            return (err1, Exp({mantissa: 0}));
        }

        return (MathError.NO_ERROR, Exp({mantissa: rational}));
    }

    /**
     * @dev Adds two exponentials, returning a new exponential.
     */
    function addExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {
        (MathError error, uint result) = addUInt(a.mantissa, b.mantissa);

        return (error, Exp({mantissa: result}));
    }

    /**
     * @dev Subtracts two exponentials, returning a new exponential.
     */
    function subExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {
        (MathError error, uint result) = subUInt(a.mantissa, b.mantissa);

        return (error, Exp({mantissa: result}));
    }

    /**
     * @dev Multiply an Exp by a scalar, returning a new Exp.
     */
    function mulScalar(Exp memory a, uint scalar) pure internal returns (MathError, Exp memory) {
        (MathError err0, uint scaledMantissa) = mulUInt(a.mantissa, scalar);
        if (err0 != MathError.NO_ERROR) {
            return (err0, Exp({mantissa: 0}));
        }

        return (MathError.NO_ERROR, Exp({mantissa: scaledMantissa}));
    }

    /**
     * @dev Multiply an Exp by a scalar, then truncate to return an unsigned integer.
     */
    function mulScalarTruncate(Exp memory a, uint scalar) pure internal returns (MathError, uint) {
        (MathError err, Exp memory product) = mulScalar(a, scalar);
        if (err != MathError.NO_ERROR) {
            return (err, 0);
        }

        return (MathError.NO_ERROR, truncate(product));
    }

    /**
     * @dev Multiply an Exp by a scalar, truncate, then add an to an unsigned integer, returning an unsigned integer.
     */
    function mulScalarTruncateAddUInt(Exp memory a, uint scalar, uint addend) pure internal returns (MathError, uint) {
        (MathError err, Exp memory product) = mulScalar(a, scalar);
        if (err != MathError.NO_ERROR) {
            return (err, 0);
        }

        return addUInt(truncate(product), addend);
    }

    /**
     * @dev Divide an Exp by a scalar, returning a new Exp.
     */
    function divScalar(Exp memory a, uint scalar) pure internal returns (MathError, Exp memory) {
        (MathError err0, uint descaledMantissa) = divUInt(a.mantissa, scalar);
        if (err0 != MathError.NO_ERROR) {
            return (err0, Exp({mantissa: 0}));
        }

        return (MathError.NO_ERROR, Exp({mantissa: descaledMantissa}));
    }

    /**
     * @dev Divide a scalar by an Exp, returning a new Exp.
     */
    function divScalarByExp(uint scalar, Exp memory divisor) pure internal returns (MathError, Exp memory) {
        /*
          We are doing this as:
          getExp(mulUInt(expScale, scalar), divisor.mantissa)

          How it works:
          Exp = a / b;
          Scalar = s;
          `s / (a / b)` = `b * s / a` and since for an Exp `a = mantissa, b = expScale`
        */
        (MathError err0, uint numerator) = mulUInt(expScale, scalar);
        if (err0 != MathError.NO_ERROR) {
            return (err0, Exp({mantissa: 0}));
        }
        return getExp(numerator, divisor.mantissa);
    }

    /**
     * @dev Divide a scalar by an Exp, then truncate to return an unsigned integer.
     */
    function divScalarByExpTruncate(uint scalar, Exp memory divisor) pure internal returns (MathError, uint) {
        (MathError err, Exp memory fraction) = divScalarByExp(scalar, divisor);
        if (err != MathError.NO_ERROR) {
            return (err, 0);
        }

        return (MathError.NO_ERROR, truncate(fraction));
    }

    /**
     * @dev Multiplies two exponentials, returning a new exponential.
     */
    function mulExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {

        (MathError err0, uint doubleScaledProduct) = mulUInt(a.mantissa, b.mantissa);
        if (err0 != MathError.NO_ERROR) {
            return (err0, Exp({mantissa: 0}));
        }

        // We add half the scale before dividing so that we get rounding instead of truncation.
        //  See "Listing 6" and text above it at https://accu.org/index.php/journals/1717
        // Without this change, a result like 6.6...e-19 will be truncated to 0 instead of being rounded to 1e-18.
        (MathError err1, uint doubleScaledProductWithHalfScale) = addUInt(halfExpScale, doubleScaledProduct);
        if (err1 != MathError.NO_ERROR) {
            return (err1, Exp({mantissa: 0}));
        }

        (MathError err2, uint product) = divUInt(doubleScaledProductWithHalfScale, expScale);
        // The only error `div` can return is MathError.DIVISION_BY_ZERO but we control `expScale` and it is not zero.
        assert(err2 == MathError.NO_ERROR);

        return (MathError.NO_ERROR, Exp({mantissa: product}));
    }

    /**
     * @dev Multiplies two exponentials given their mantissas, returning a new exponential.
     */
    function mulExp(uint a, uint b) pure internal returns (MathError, Exp memory) {
        return mulExp(Exp({mantissa: a}), Exp({mantissa: b}));
    }

    /**
     * @dev Multiplies three exponentials, returning a new exponential.
     */
    function mulExp3(Exp memory a, Exp memory b, Exp memory c) pure internal returns (MathError, Exp memory) {
        (MathError err, Exp memory ab) = mulExp(a, b);
        if (err != MathError.NO_ERROR) {
            return (err, ab);
        }
        return mulExp(ab, c);
    }

    /**
     * @dev Divides two exponentials, returning a new exponential.
     *     (a/scale) / (b/scale) = (a/scale) * (scale/b) = a/b,
     *  which we can scale as an Exp by calling getExp(a.mantissa, b.mantissa)
     */
    function divExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {
        return getExp(a.mantissa, b.mantissa);
    }

    /**
     * @dev Truncates the given exp to a whole number value.
     *      For example, truncate(Exp{mantissa: 15 * expScale}) = 15
     */
    function truncate(Exp memory exp) pure internal returns (uint) {
        // Note: We are not using careful math here as we're performing a division that cannot fail
        return exp.mantissa / expScale;
    }

    /**
     * @dev Checks if first Exp is less than second Exp.
     */
    function lessThanExp(Exp memory left, Exp memory right) pure internal returns (bool) {
        return left.mantissa < right.mantissa; //TODO: Add some simple tests and this in another PR yo.
    }

    /**
     * @dev Checks if left Exp <= right Exp.
     */
    function lessThanOrEqualExp(Exp memory left, Exp memory right) pure internal returns (bool) {
        return left.mantissa <= right.mantissa;
    }

    /**
     * @dev returns true if Exp is exactly zero
     */
    function isZeroExp(Exp memory value) pure internal returns (bool) {
        return value.mantissa == 0;
    }
}

// File: contracts/EIP20Interface.sol

pragma solidity ^0.5.8;

/**
 * @title ERC 20 Token Standard Interface
 *  https://eips.ethereum.org/EIPS/eip-20
 */
interface EIP20Interface {

    /**
      * @notice Get the total number of tokens in circulation
      * @return The supply of tokens
      */
    function totalSupply() external view returns (uint256);

    /**
     * @notice Gets the balance of the specified address
     * @param owner The address from which the balance will be retrieved
     * @return The balance
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    /**
      * @notice Transfer `amount` tokens from `msg.sender` to `dst`
      * @param dst The address of the destination account
      * @param amount The number of tokens to transfer
      * @return Whether or not the transfer succeeded
      */
    function transfer(address dst, uint256 amount) external returns (bool success);

    /**
      * @notice Transfer `amount` tokens from `src` to `dst`
      * @param src The address of the source account
      * @param dst The address of the destination account
      * @param amount The number of tokens to transfer
      * @return Whether or not the transfer succeeded
      */
    function transferFrom(address src, address dst, uint256 amount) external returns (bool success);

    /**
      * @notice Approve `spender` to transfer up to `amount` from `src`
      * @dev This will overwrite the approval amount for `spender`
      *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
      * @param spender The address of the account which may transfer tokens
      * @param amount The number of tokens that are approved (-1 means infinite)
      * @return Whether or not the approval succeeded
      */
    function approve(address spender, uint256 amount) external returns (bool success);

    /**
      * @notice Get the current allowance from `owner` for `spender`
      * @param owner The address of the account which owns the tokens to be spent
      * @param spender The address of the account which may transfer tokens
      * @return The number of tokens allowed to be spent (-1 means infinite)
      */
    function allowance(address owner, address spender) external view returns (uint256 remaining);

    event Transfer(address indexed from, address indexed to, uint256 amount);
    event Approval(address indexed owner, address indexed spender, uint256 amount);
}

// File: contracts/EIP20NonStandardInterface.sol

pragma solidity ^0.5.8;

/**
 * @title EIP20NonStandardInterface
 * @dev Version of ERC20 with no return values for `transfer` and `transferFrom`
 *  See https://medium.com/coinmonks/missing-return-value-bug-at-least-130-tokens-affected-d67bf08521ca
 */
interface EIP20NonStandardInterface {

    /**
     * @notice Get the total number of tokens in circulation
     * @return The supply of tokens
     */
    function totalSupply() external view returns (uint256);

    /**
     * @notice Gets the balance of the specified address
     * @param owner The address from which the balance will be retrieved
     * @return The balance
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    ///
    /// !!!!!!!!!!!!!!
    /// !!! NOTICE !!! `transfer` does not return a value, in violation of the ERC-20 specification
    /// !!!!!!!!!!!!!!
    ///

    /**
      * @notice Transfer `amount` tokens from `msg.sender` to `dst`
      * @param dst The address of the destination account
      * @param amount The number of tokens to transfer
      */
    function transfer(address dst, uint256 amount) external;

    ///
    /// !!!!!!!!!!!!!!
    /// !!! NOTICE !!! `transferFrom` does not return a value, in violation of the ERC-20 specification
    /// !!!!!!!!!!!!!!
    ///

    /**
      * @notice Transfer `amount` tokens from `src` to `dst`
      * @param src The address of the source account
      * @param dst The address of the destination account
      * @param amount The number of tokens to transfer
      */
    function transferFrom(address src, address dst, uint256 amount) external;

    /**
      * @notice Approve `spender` to transfer up to `amount` from `src`
      * @dev This will overwrite the approval amount for `spender`
      *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
      * @param spender The address of the account which may transfer tokens
      * @param amount The number of tokens that are approved
      * @return Whether or not the approval succeeded
      */
    function approve(address spender, uint256 amount) external returns (bool success);

    /**
      * @notice Get the current allowance from `owner` for `spender`
      * @param owner The address of the account which owns the tokens to be spent
      * @param spender The address of the account which may transfer tokens
      * @return The number of tokens allowed to be spent
      */
    function allowance(address owner, address spender) external view returns (uint256 remaining);

    event Transfer(address indexed from, address indexed to, uint256 amount);
    event Approval(address indexed owner, address indexed spender, uint256 amount);
}

// File: contracts/ReentrancyGuard.sol

pragma solidity ^0.5.8;

/**
 * @title Helps contracts guard against reentrancy attacks.
 * @author Remco Bloemen <remco@2π.com>, Eenae <[email protected]>
 * @dev If you mark a function `nonReentrant`, you should also
 * mark it `external`.
 */
contract ReentrancyGuard {
    /// @dev counter to allow mutex lock with only one SSTORE operation
    uint256 private _guardCounter;

    constructor () internal {
        // The counter starts at one to prevent changing it from zero to a non-zero
        // value, which is a more expensive operation.
        _guardCounter = 1;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        _guardCounter += 1;
        uint256 localCounter = _guardCounter;
        _;
        require(localCounter == _guardCounter, "re-entered");
    }
}

// File: contracts/InterestRateModel.sol

pragma solidity ^0.5.8;

/**
  * @title The Compound InterestRateModel Interface
  * @author Compound
  * @notice Any interest rate model should derive from this contract.
  * @dev These functions are specifically not marked `pure` as implementations of this
  *      contract may read from storage variables.
  */
interface InterestRateModel {
    /**
      * @notice Gets the current borrow interest rate based on the given asset, total cash, total borrows
      *         and total reserves.
      * @dev The return value should be scaled by 1e18, thus a return value of
      *      `(true, 1000000000000)` implies an interest rate of 0.000001 or 0.0001% *per block*.
      * @param cash The total cash of the underlying asset in the CToken
      * @param borrows The total borrows of the underlying asset in the CToken
      * @param reserves The total reserves of the underlying asset in the CToken
      * @return Success or failure and the borrow interest rate per block scaled by 10e18
      */
    function getBorrowRate(uint cash, uint borrows, uint reserves) external view returns (uint, uint);

    /**
      * @notice Marker function used for light validation when updating the interest rate model of a market
      * @dev Marker function used for light validation when updating the interest rate model of a market. Implementations should simply return true.
      * @return Success or failure
      */
    function isInterestRateModel() external view returns (bool);
}

// File: contracts/CToken.sol

pragma solidity ^0.5.8;








/**
 * @title Compound's CToken Contract
 * @notice Abstract base for CTokens
 * @author Compound
 */
contract CToken is EIP20Interface, Exponential, TokenErrorReporter, ReentrancyGuard {
    /**
     * @notice Indicator that this is a CToken contract (for inspection)
     */
    bool public constant isCToken = true;

    /**
     * @notice EIP-20 token name for this token
     */
    string public name;

    /**
     * @notice EIP-20 token symbol for this token
     */
    string public symbol;

    /**
     * @notice EIP-20 token decimals for this token
     */
    uint public decimals;

    /**
     * @notice Maximum borrow rate that can ever be applied (.0005% / block)
     */
    uint constant borrowRateMaxMantissa = 5e14;

    /**
     * @notice Maximum fraction of interest that can be set aside for reserves
     */
    uint constant reserveFactorMaxMantissa = 1e18;

    /**
     * @notice Administrator for this contract
     */
    address payable public admin;

    /**
     * @notice Pending administrator for this contract
     */
    address payable public pendingAdmin;

    /**
     * @notice Contract which oversees inter-cToken operations
     */
    ComptrollerInterface public comptroller;

    /**
     * @notice Model which tells what the current interest rate should be
     */
    InterestRateModel public interestRateModel;

    /**
     * @notice Initial exchange rate used when minting the first CTokens (used when totalSupply = 0)
     */
    uint public initialExchangeRateMantissa;

    /**
     * @notice Fraction of interest currently set aside for reserves
     */
    uint public reserveFactorMantissa;

    /**
     * @notice Block number that interest was last accrued at
     */
    uint public accrualBlockNumber;

    /**
     * @notice Accumulator of total earned interest since the opening of the market
     */
    uint public borrowIndex;

    /**
     * @notice Total amount of outstanding borrows of the underlying in this market
     */
    uint public totalBorrows;

    /**
     * @notice Total amount of reserves of the underlying held in this market
     */
    uint public totalReserves;

    /**
     * @notice Total number of tokens in circulation
     */
    uint256 public totalSupply;

    /**
     * @notice Official record of token balances for each account
     */
    mapping (address => uint256) accountTokens;

    /**
     * @notice Approved token transfer amounts on behalf of others
     */
    mapping (address => mapping (address => uint256)) transferAllowances;

    /**
     * @notice Container for borrow balance information
     * @member principal Total balance (with accrued interest), after applying the most recent balance-changing action
     * @member interestIndex Global borrowIndex as of the most recent balance-changing action
     */
    struct BorrowSnapshot {
        uint principal;
        uint interestIndex;
    }

    /**
     * @notice Mapping of account addresses to outstanding borrow balances
     */
    mapping(address => BorrowSnapshot) accountBorrows;


    /*** Market Events ***/

    /**
     * @notice Event emitted when interest is accrued
     */
    event AccrueInterest(uint interestAccumulated, uint borrowIndex, uint totalBorrows);

    /**
     * @notice Event emitted when tokens are minted
     */
    event Mint(address minter, uint mintAmount, uint mintTokens);

    /**
     * @notice Event emitted when tokens are redeemed
     */
    event Redeem(address redeemer, uint redeemAmount, uint redeemTokens);

    /**
     * @notice Event emitted when underlying is borrowed
     */
    event Borrow(address borrower, uint borrowAmount, uint accountBorrows, uint totalBorrows);

    /**
     * @notice Event emitted when a borrow is repaid
     */
    event RepayBorrow(address payer, address borrower, uint repayAmount, uint accountBorrows, uint totalBorrows);

    /**
     * @notice Event emitted when a borrow is liquidated
     */
    event LiquidateBorrow(address liquidator, address borrower, uint repayAmount, address cTokenCollateral, uint seizeTokens);


    /*** Admin Events ***/

    /**
     * @notice Event emitted when pendingAdmin is changed
     */
    event NewPendingAdmin(address oldPendingAdmin, address newPendingAdmin);

    /**
     * @notice Event emitted when pendingAdmin is accepted, which means admin is updated
     */
    event NewAdmin(address oldAdmin, address newAdmin);

    /**
     * @notice Event emitted when comptroller is changed
     */
    event NewComptroller(ComptrollerInterface oldComptroller, ComptrollerInterface newComptroller);

    /**
     * @notice Event emitted when interestRateModel is changed
     */
    event NewMarketInterestRateModel(InterestRateModel oldInterestRateModel, InterestRateModel newInterestRateModel);

    /**
     * @notice Event emitted when the reserve factor is changed
     */
    event NewReserveFactor(uint oldReserveFactorMantissa, uint newReserveFactorMantissa);

    /**
     * @notice Event emitted when the reserves are reduced
     */
    event ReservesReduced(address admin, uint reduceAmount, uint newTotalReserves);


    /**
     * @notice Construct a new money market
     * @param comptroller_ The address of the Comptroller
     * @param interestRateModel_ The address of the interest rate model
     * @param initialExchangeRateMantissa_ The initial exchange rate, scaled by 1e18
     * @param name_ EIP-20 name of this token
     * @param symbol_ EIP-20 symbol of this token
     * @param decimals_ EIP-20 decimal precision of this token
     */
    constructor(ComptrollerInterface comptroller_,
                InterestRateModel interestRateModel_,
                uint initialExchangeRateMantissa_,
                string memory name_,
                string memory symbol_,
                uint decimals_) internal {
        // Set admin to msg.sender
        admin = msg.sender;

        // Set initial exchange rate
        initialExchangeRateMantissa = initialExchangeRateMantissa_;
        require(initialExchangeRateMantissa > 0, "Initial exchange rate must be greater than zero.");

        // Set the comptroller
        uint err = _setComptroller(comptroller_);
        require(err == uint(Error.NO_ERROR), "Setting comptroller failed");

        // Initialize block number and borrow index (block number mocks depend on comptroller being set)
        accrualBlockNumber = getBlockNumber();
        borrowIndex = mantissaOne;

        // Set the interest rate model (depends on block number / borrow index)
        err = _setInterestRateModelFresh(interestRateModel_);
        require(err == uint(Error.NO_ERROR), "Setting interest rate model failed");

        name = name_;
        symbol = symbol_;
        decimals = decimals_;
    }

    /**
     * @notice Transfer `tokens` tokens from `src` to `dst` by `spender`
     * @dev Called by both `transfer` and `transferFrom` internally
     * @param spender The address of the account performing the transfer
     * @param src The address of the source account
     * @param dst The address of the destination account
     * @param tokens The number of tokens to transfer
     * @return Whether or not the transfer succeeded
     */
    function transferTokens(address spender, address src, address dst, uint tokens) internal returns (uint) {
        /* Fail if transfer not allowed */
        uint allowed = comptroller.transferAllowed(address(this), src, dst, tokens);
        if (allowed != 0) {
            return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.TRANSFER_COMPTROLLER_REJECTION, allowed);
        }

        /* Do not allow self-transfers */
        if (src == dst) {
            return fail(Error.BAD_INPUT, FailureInfo.TRANSFER_NOT_ALLOWED);
        }

        /* Get the allowance, infinite for the account owner */
        uint startingAllowance = 0;
        if (spender == src) {
            startingAllowance = uint(-1);
        } else {
            startingAllowance = transferAllowances[src][spender];
        }

        /* Do the calculations, checking for {under,over}flow */
        MathError mathErr;
        uint allowanceNew;
        uint srcTokensNew;
        uint dstTokensNew;

        (mathErr, allowanceNew) = subUInt(startingAllowance, tokens);
        if (mathErr != MathError.NO_ERROR) {
            return fail(Error.MATH_ERROR, FailureInfo.TRANSFER_NOT_ALLOWED);
        }

        (mathErr, srcTokensNew) = subUInt(accountTokens[src], tokens);
        if (mathErr != MathError.NO_ERROR) {
            return fail(Error.MATH_ERROR, FailureInfo.TRANSFER_NOT_ENOUGH);
        }

        (mathErr, dstTokensNew) = addUInt(accountTokens[dst], tokens);
        if (mathErr != MathError.NO_ERROR) {
            return fail(Error.MATH_ERROR, FailureInfo.TRANSFER_TOO_MUCH);
        }

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        accountTokens[src] = srcTokensNew;
        accountTokens[dst] = dstTokensNew;

        /* Eat some of the allowance (if necessary) */
        if (startingAllowance != uint(-1)) {
            transferAllowances[src][spender] = allowanceNew;
        }

        /* We emit a Transfer event */
        emit Transfer(src, dst, tokens);

        /* We call the defense hook (which checks for under-collateralization) */
        comptroller.transferVerify(address(this), src, dst, tokens);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Transfer `amount` tokens from `msg.sender` to `dst`
     * @param dst The address of the destination account
     * @param amount The number of tokens to transfer
     * @return Whether or not the transfer succeeded
     */
    function transfer(address dst, uint256 amount) external nonReentrant returns (bool) {
        return transferTokens(msg.sender, msg.sender, dst, amount) == uint(Error.NO_ERROR);
    }

    /**
     * @notice Transfer `amount` tokens from `src` to `dst`
     * @param src The address of the source account
     * @param dst The address of the destination account
     * @param amount The number of tokens to transfer
     * @return Whether or not the transfer succeeded
     */
    function transferFrom(address src, address dst, uint256 amount) external nonReentrant returns (bool) {
        return transferTokens(msg.sender, src, dst, amount) == uint(Error.NO_ERROR);
    }

    /**
     * @notice Approve `spender` to transfer up to `amount` from `src`
     * @dev This will overwrite the approval amount for `spender`
     *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
     * @param spender The address of the account which may transfer tokens
     * @param amount The number of tokens that are approved (-1 means infinite)
     * @return Whether or not the approval succeeded
     */
    function approve(address spender, uint256 amount) external returns (bool) {
        address src = msg.sender;
        transferAllowances[src][spender] = amount;
        emit Approval(src, spender, amount);
        return true;
    }

    /**
     * @notice Get the current allowance from `owner` for `spender`
     * @param owner The address of the account which owns the tokens to be spent
     * @param spender The address of the account which may transfer tokens
     * @return The number of tokens allowed to be spent (-1 means infinite)
     */
    function allowance(address owner, address spender) external view returns (uint256) {
        return transferAllowances[owner][spender];
    }

    /**
     * @notice Get the token balance of the `owner`
     * @param owner The address of the account to query
     * @return The number of tokens owned by `owner`
     */
    function balanceOf(address owner) external view returns (uint256) {
        return accountTokens[owner];
    }

    /**
     * @notice Get the underlying balance of the `owner`
     * @dev This also accrues interest in a transaction
     * @param owner The address of the account to query
     * @return The amount of underlying owned by `owner`
     */
    function balanceOfUnderlying(address owner) external returns (uint) {
        Exp memory exchangeRate = Exp({mantissa: exchangeRateCurrent()});
        (MathError mErr, uint balance) = mulScalarTruncate(exchangeRate, accountTokens[owner]);
        require(mErr == MathError.NO_ERROR);
        return balance;
    }

    /**
     * @notice Get a snapshot of the account's balances, and the cached exchange rate
     * @dev This is used by comptroller to more efficiently perform liquidity checks.
     * @param account Address of the account to snapshot
     * @return (possible error, token balance, borrow balance, exchange rate mantissa)
     */
    function getAccountSnapshot(address account) external view returns (uint, uint, uint, uint) {
        uint cTokenBalance = accountTokens[account];
        uint borrowBalance;
        uint exchangeRateMantissa;

        MathError mErr;

        (mErr, borrowBalance) = borrowBalanceStoredInternal(account);
        if (mErr != MathError.NO_ERROR) {
            return (uint(Error.MATH_ERROR), 0, 0, 0);
        }

        (mErr, exchangeRateMantissa) = exchangeRateStoredInternal();
        if (mErr != MathError.NO_ERROR) {
            return (uint(Error.MATH_ERROR), 0, 0, 0);
        }

        return (uint(Error.NO_ERROR), cTokenBalance, borrowBalance, exchangeRateMantissa);
    }

    /**
     * @dev Function to simply retrieve block number
     *  This exists mainly for inheriting test contracts to stub this result.
     */
    function getBlockNumber() internal view returns (uint) {
        return block.number;
    }

    /**
     * @notice Returns the current per-block borrow interest rate for this cToken
     * @return The borrow interest rate per block, scaled by 1e18
     */
    function borrowRatePerBlock() external view returns (uint) {
        (uint opaqueErr, uint borrowRateMantissa) = interestRateModel.getBorrowRate(getCashPrior(), totalBorrows, totalReserves);
        require(opaqueErr == 0, "borrowRatePerBlock: interestRateModel.borrowRate failed"); // semi-opaque
        return borrowRateMantissa;
    }

    /**
     * @notice Returns the current per-block supply interest rate for this cToken
     * @return The supply interest rate per block, scaled by 1e18
     */
    function supplyRatePerBlock() external view returns (uint) {
        /* We calculate the supply rate:
         *  underlying = totalSupply × exchangeRate
         *  borrowsPer = totalBorrows ÷ underlying
         *  supplyRate = borrowRate × (1-reserveFactor) × borrowsPer
         */
        uint exchangeRateMantissa = exchangeRateStored();

        (uint e0, uint borrowRateMantissa) = interestRateModel.getBorrowRate(getCashPrior(), totalBorrows, totalReserves);
        require(e0 == 0, "supplyRatePerBlock: calculating borrowRate failed"); // semi-opaque

        (MathError e1, Exp memory underlying) = mulScalar(Exp({mantissa: exchangeRateMantissa}), totalSupply);
        require(e1 == MathError.NO_ERROR, "supplyRatePerBlock: calculating underlying failed");

        (MathError e2, Exp memory borrowsPer) = divScalarByExp(totalBorrows, underlying);
        require(e2 == MathError.NO_ERROR, "supplyRatePerBlock: calculating borrowsPer failed");

        (MathError e3, Exp memory oneMinusReserveFactor) = subExp(Exp({mantissa: mantissaOne}), Exp({mantissa: reserveFactorMantissa}));
        require(e3 == MathError.NO_ERROR, "supplyRatePerBlock: calculating oneMinusReserveFactor failed");

        (MathError e4, Exp memory supplyRate) = mulExp3(Exp({mantissa: borrowRateMantissa}), oneMinusReserveFactor, borrowsPer);
        require(e4 == MathError.NO_ERROR, "supplyRatePerBlock: calculating supplyRate failed");

        return supplyRate.mantissa;
    }

    /**
     * @notice Returns the current total borrows plus accrued interest
     * @return The total borrows with interest
     */
    function totalBorrowsCurrent() external nonReentrant returns (uint) {
        require(accrueInterest() == uint(Error.NO_ERROR), "accrue interest failed");
        return totalBorrows;
    }

    /**
     * @notice Accrue interest to updated borrowIndex and then calculate account's borrow balance using the updated borrowIndex
     * @param account The address whose balance should be calculated after updating borrowIndex
     * @return The calculated balance
     */
    function borrowBalanceCurrent(address account) external nonReentrant returns (uint) {
        require(accrueInterest() == uint(Error.NO_ERROR), "accrue interest failed");
        return borrowBalanceStored(account);
    }

    /**
     * @notice Return the borrow balance of account based on stored data
     * @param account The address whose balance should be calculated
     * @return The calculated balance
     */
    function borrowBalanceStored(address account) public view returns (uint) {
        (MathError err, uint result) = borrowBalanceStoredInternal(account);
        require(err == MathError.NO_ERROR, "borrowBalanceStored: borrowBalanceStoredInternal failed");
        return result;
    }

    /**
     * @notice Return the borrow balance of account based on stored data
     * @param account The address whose balance should be calculated
     * @return (error code, the calculated balance or 0 if error code is non-zero)
     */
    function borrowBalanceStoredInternal(address account) internal view returns (MathError, uint) {
        /* Note: we do not assert that the market is up to date */
        MathError mathErr;
        uint principalTimesIndex;
        uint result;

        /* Get borrowBalance and borrowIndex */
        BorrowSnapshot storage borrowSnapshot = accountBorrows[account];

        /* If borrowBalance = 0 then borrowIndex is likely also 0.
         * Rather than failing the calculation with a division by 0, we immediately return 0 in this case.
         */
        if (borrowSnapshot.principal == 0) {
            return (MathError.NO_ERROR, 0);
        }

        /* Calculate new borrow balance using the interest index:
         *  recentBorrowBalance = borrower.borrowBalance * market.borrowIndex / borrower.borrowIndex
         */
        (mathErr, principalTimesIndex) = mulUInt(borrowSnapshot.principal, borrowIndex);
        if (mathErr != MathError.NO_ERROR) {
            return (mathErr, 0);
        }

        (mathErr, result) = divUInt(principalTimesIndex, borrowSnapshot.interestIndex);
        if (mathErr != MathError.NO_ERROR) {
            return (mathErr, 0);
        }

        return (MathError.NO_ERROR, result);
    }

    /**
     * @notice Accrue interest then return the up-to-date exchange rate
     * @return Calculated exchange rate scaled by 1e18
     */
    function exchangeRateCurrent() public nonReentrant returns (uint) {
        require(accrueInterest() == uint(Error.NO_ERROR), "accrue interest failed");
        return exchangeRateStored();
    }

    /**
     * @notice Calculates the exchange rate from the underlying to the CToken
     * @dev This function does not accrue interest before calculating the exchange rate
     * @return Calculated exchange rate scaled by 1e18
     */
    function exchangeRateStored() public view returns (uint) {
        (MathError err, uint result) = exchangeRateStoredInternal();
        require(err == MathError.NO_ERROR, "exchangeRateStored: exchangeRateStoredInternal failed");
        return result;
    }

    /**
     * @notice Calculates the exchange rate from the underlying to the CToken
     * @dev This function does not accrue interest before calculating the exchange rate
     * @return (error code, calculated exchange rate scaled by 1e18)
     */
    function exchangeRateStoredInternal() internal view returns (MathError, uint) {
        if (totalSupply == 0) {
            /*
             * If there are no tokens minted:
             *  exchangeRate = initialExchangeRate
             */
            return (MathError.NO_ERROR, initialExchangeRateMantissa);
        } else {
            /*
             * Otherwise:
             *  exchangeRate = (totalCash + totalBorrows - totalReserves) / totalSupply
             */
            uint totalCash = getCashPrior();
            uint cashPlusBorrowsMinusReserves;
            Exp memory exchangeRate;
            MathError mathErr;

            (mathErr, cashPlusBorrowsMinusReserves) = addThenSubUInt(totalCash, totalBorrows, totalReserves);
            if (mathErr != MathError.NO_ERROR) {
                return (mathErr, 0);
            }

            (mathErr, exchangeRate) = getExp(cashPlusBorrowsMinusReserves, totalSupply);
            if (mathErr != MathError.NO_ERROR) {
                return (mathErr, 0);
            }

            return (MathError.NO_ERROR, exchangeRate.mantissa);
        }
    }

    /**
     * @notice Get cash balance of this cToken in the underlying asset
     * @return The quantity of underlying asset owned by this contract
     */
    function getCash() external view returns (uint) {
        return getCashPrior();
    }

    struct AccrueInterestLocalVars {
        MathError mathErr;
        uint opaqueErr;
        uint borrowRateMantissa;
        uint currentBlockNumber;
        uint blockDelta;

        Exp simpleInterestFactor;

        uint interestAccumulated;
        uint totalBorrowsNew;
        uint totalReservesNew;
        uint borrowIndexNew;
    }

    /**
      * @notice Applies accrued interest to total borrows and reserves.
      * @dev This calculates interest accrued from the last checkpointed block
      *      up to the current block and writes new checkpoint to storage.
      */
    function accrueInterest() public returns (uint) {
        AccrueInterestLocalVars memory vars;

        /* Calculate the current borrow interest rate */
        (vars.opaqueErr, vars.borrowRateMantissa) = interestRateModel.getBorrowRate(getCashPrior(), totalBorrows, totalReserves);
        require(vars.borrowRateMantissa <= borrowRateMaxMantissa, "borrow rate is absurdly high");
        if (vars.opaqueErr != 0) {
            return failOpaque(Error.INTEREST_RATE_MODEL_ERROR, FailureInfo.ACCRUE_INTEREST_BORROW_RATE_CALCULATION_FAILED, vars.opaqueErr);
        }

        /* Remember the initial block number */
        vars.currentBlockNumber = getBlockNumber();

        /* Calculate the number of blocks elapsed since the last accrual */
        (vars.mathErr, vars.blockDelta) = subUInt(vars.currentBlockNumber, accrualBlockNumber);
        assert(vars.mathErr == MathError.NO_ERROR); // Block delta should always succeed and if it doesn't, blow up.

        /*
         * Calculate the interest accumulated into borrows and reserves and the new index:
         *  simpleInterestFactor = borrowRate * blockDelta
         *  interestAccumulated = simpleInterestFactor * totalBorrows
         *  totalBorrowsNew = interestAccumulated + totalBorrows
         *  totalReservesNew = interestAccumulated * reserveFactor + totalReserves
         *  borrowIndexNew = simpleInterestFactor * borrowIndex + borrowIndex
         */
        (vars.mathErr, vars.simpleInterestFactor) = mulScalar(Exp({mantissa: vars.borrowRateMantissa}), vars.blockDelta);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_SIMPLE_INTEREST_FACTOR_CALCULATION_FAILED, uint(vars.mathErr));
        }

        (vars.mathErr, vars.interestAccumulated) = mulScalarTruncate(vars.simpleInterestFactor, totalBorrows);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_ACCUMULATED_INTEREST_CALCULATION_FAILED, uint(vars.mathErr));
        }

        (vars.mathErr, vars.totalBorrowsNew) = addUInt(vars.interestAccumulated, totalBorrows);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_NEW_TOTAL_BORROWS_CALCULATION_FAILED, uint(vars.mathErr));
        }

        (vars.mathErr, vars.totalReservesNew) = mulScalarTruncateAddUInt(Exp({mantissa: reserveFactorMantissa}), vars.interestAccumulated, totalReserves);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_NEW_TOTAL_RESERVES_CALCULATION_FAILED, uint(vars.mathErr));
        }

        (vars.mathErr, vars.borrowIndexNew) = mulScalarTruncateAddUInt(vars.simpleInterestFactor, borrowIndex, borrowIndex);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_NEW_BORROW_INDEX_CALCULATION_FAILED, uint(vars.mathErr));
        }

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        /* We write the previously calculated values into storage */
        accrualBlockNumber = vars.currentBlockNumber;
        borrowIndex = vars.borrowIndexNew;
        totalBorrows = vars.totalBorrowsNew;
        totalReserves = vars.totalReservesNew;

        /* We emit an AccrueInterest event */
        emit AccrueInterest(vars.interestAccumulated, vars.borrowIndexNew, totalBorrows);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Sender supplies assets into the market and receives cTokens in exchange
     * @dev Accrues interest whether or not the operation succeeds, unless reverted
     * @param mintAmount The amount of the underlying asset to supply
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function mintInternal(uint mintAmount) internal nonReentrant returns (uint) {
        uint error = accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
            return fail(Error(error), FailureInfo.MINT_ACCRUE_INTEREST_FAILED);
        }
        // mintFresh emits the actual Mint event if successful and logs on errors, so we don't need to
        return mintFresh(msg.sender, mintAmount);
    }

    struct MintLocalVars {
        Error err;
        MathError mathErr;
        uint exchangeRateMantissa;
        uint mintTokens;
        uint totalSupplyNew;
        uint accountTokensNew;
    }

    /**
     * @notice User supplies assets into the market and receives cTokens in exchange
     * @dev Assumes interest has already been accrued up to the current block
     * @param minter The address of the account which is supplying the assets
     * @param mintAmount The amount of the underlying asset to supply
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function mintFresh(address minter, uint mintAmount) internal returns (uint) {
        /* Fail if mint not allowed */
        uint allowed = comptroller.mintAllowed(address(this), minter, mintAmount);
        if (allowed != 0) {
            return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.MINT_COMPTROLLER_REJECTION, allowed);
        }

        /* Verify market's block number equals current block number */
        if (accrualBlockNumber != getBlockNumber()) {
            return fail(Error.MARKET_NOT_FRESH, FailureInfo.MINT_FRESHNESS_CHECK);
        }

        MintLocalVars memory vars;

        /* Fail if checkTransferIn fails */
        vars.err = checkTransferIn(minter, mintAmount);
        if (vars.err != Error.NO_ERROR) {
            return fail(vars.err, FailureInfo.MINT_TRANSFER_IN_NOT_POSSIBLE);
        }

        /*
         * We get the current exchange rate and calculate the number of cTokens to be minted:
         *  mintTokens = mintAmount / exchangeRate
         */
        (vars.mathErr, vars.exchangeRateMantissa) = exchangeRateStoredInternal();
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.MINT_EXCHANGE_RATE_READ_FAILED, uint(vars.mathErr));
        }

        (vars.mathErr, vars.mintTokens) = divScalarByExpTruncate(mintAmount, Exp({mantissa: vars.exchangeRateMantissa}));
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.MINT_EXCHANGE_CALCULATION_FAILED, uint(vars.mathErr));
        }

        /*
         * We calculate the new total supply of cTokens and minter token balance, checking for overflow:
         *  totalSupplyNew = totalSupply + mintTokens
         *  accountTokensNew = accountTokens[minter] + mintTokens
         */
        (vars.mathErr, vars.totalSupplyNew) = addUInt(totalSupply, vars.mintTokens);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.MINT_NEW_TOTAL_SUPPLY_CALCULATION_FAILED, uint(vars.mathErr));
        }

        (vars.mathErr, vars.accountTokensNew) = addUInt(accountTokens[minter], vars.mintTokens);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.MINT_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
        }

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        /*
         * We call doTransferIn for the minter and the mintAmount
         *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
         *  On success, the cToken holds an additional mintAmount of cash.
         *  If doTransferIn fails despite the fact we checked pre-conditions,
         *   we revert because we can't be sure if side effects occurred.
         */
        vars.err = doTransferIn(minter, mintAmount);
        if (vars.err != Error.NO_ERROR) {
            return fail(vars.err, FailureInfo.MINT_TRANSFER_IN_FAILED);
        }

        /* We write previously calculated values into storage */
        totalSupply = vars.totalSupplyNew;
        accountTokens[minter] = vars.accountTokensNew;

        /* We emit a Mint event, and a Transfer event */
        emit Mint(minter, mintAmount, vars.mintTokens);
        emit Transfer(address(this), minter, vars.mintTokens);

        /* We call the defense hook */
        comptroller.mintVerify(address(this), minter, mintAmount, vars.mintTokens);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Sender redeems cTokens in exchange for the underlying asset
     * @dev Accrues interest whether or not the operation succeeds, unless reverted
     * @param redeemTokens The number of cTokens to redeem into underlying
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function redeemInternal(uint redeemTokens) internal nonReentrant returns (uint) {
        uint error = accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted redeem failed
            return fail(Error(error), FailureInfo.REDEEM_ACCRUE_INTEREST_FAILED);
        }
        // redeemFresh emits redeem-specific logs on errors, so we don't need to
        return redeemFresh(msg.sender, redeemTokens, 0);
    }

    /**
     * @notice Sender redeems cTokens in exchange for a specified amount of underlying asset
     * @dev Accrues interest whether or not the operation succeeds, unless reverted
     * @param redeemAmount The amount of underlying to redeem
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function redeemUnderlyingInternal(uint redeemAmount) internal nonReentrant returns (uint) {
        uint error = accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted redeem failed
            return fail(Error(error), FailureInfo.REDEEM_ACCRUE_INTEREST_FAILED);
        }
        // redeemFresh emits redeem-specific logs on errors, so we don't need to
        return redeemFresh(msg.sender, 0, redeemAmount);
    }

    struct RedeemLocalVars {
        Error err;
        MathError mathErr;
        uint exchangeRateMantissa;
        uint redeemTokens;
        uint redeemAmount;
        uint totalSupplyNew;
        uint accountTokensNew;
    }

    /**
     * @notice User redeems cTokens in exchange for the underlying asset
     * @dev Assumes interest has already been accrued up to the current block
     * @param redeemer The address of the account which is redeeming the tokens
     * @param redeemTokensIn The number of cTokens to redeem into underlying (only one of redeemTokensIn or redeemAmountIn may be zero)
     * @param redeemAmountIn The number of cTokens to redeem into underlying (only one of redeemTokensIn or redeemAmountIn may be zero)
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function redeemFresh(address payable redeemer, uint redeemTokensIn, uint redeemAmountIn) internal returns (uint) {
        require(redeemTokensIn == 0 || redeemAmountIn == 0, "one of redeemTokensIn or redeemAmountIn must be zero");

        RedeemLocalVars memory vars;

        /* exchangeRate = invoke Exchange Rate Stored() */
        (vars.mathErr, vars.exchangeRateMantissa) = exchangeRateStoredInternal();
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_EXCHANGE_RATE_READ_FAILED, uint(vars.mathErr));
        }

        /* If redeemTokensIn > 0: */
        if (redeemTokensIn > 0) {
            /*
             * We calculate the exchange rate and the amount of underlying to be redeemed:
             *  redeemTokens = redeemTokensIn
             *  redeemAmount = redeemTokensIn x exchangeRateCurrent
             */
            vars.redeemTokens = redeemTokensIn;

            (vars.mathErr, vars.redeemAmount) = mulScalarTruncate(Exp({mantissa: vars.exchangeRateMantissa}), redeemTokensIn);
            if (vars.mathErr != MathError.NO_ERROR) {
                return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_EXCHANGE_TOKENS_CALCULATION_FAILED, uint(vars.mathErr));
            }
        } else {
            /*
             * We get the current exchange rate and calculate the amount to be redeemed:
             *  redeemTokens = redeemAmountIn / exchangeRate
             *  redeemAmount = redeemAmountIn
             */

            (vars.mathErr, vars.redeemTokens) = divScalarByExpTruncate(redeemAmountIn, Exp({mantissa: vars.exchangeRateMantissa}));
            if (vars.mathErr != MathError.NO_ERROR) {
                return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_EXCHANGE_AMOUNT_CALCULATION_FAILED, uint(vars.mathErr));
            }

            vars.redeemAmount = redeemAmountIn;
        }

        /* Fail if redeem not allowed */
        uint allowed = comptroller.redeemAllowed(address(this), redeemer, vars.redeemTokens);
        if (allowed != 0) {
            return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.REDEEM_COMPTROLLER_REJECTION, allowed);
        }

        /* Verify market's block number equals current block number */
        if (accrualBlockNumber != getBlockNumber()) {
            return fail(Error.MARKET_NOT_FRESH, FailureInfo.REDEEM_FRESHNESS_CHECK);
        }

        /*
         * We calculate the new total supply and redeemer balance, checking for underflow:
         *  totalSupplyNew = totalSupply - redeemTokens
         *  accountTokensNew = accountTokens[redeemer] - redeemTokens
         */
        (vars.mathErr, vars.totalSupplyNew) = subUInt(totalSupply, vars.redeemTokens);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_NEW_TOTAL_SUPPLY_CALCULATION_FAILED, uint(vars.mathErr));
        }

        (vars.mathErr, vars.accountTokensNew) = subUInt(accountTokens[redeemer], vars.redeemTokens);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
        }

        /* Fail gracefully if protocol has insufficient cash */
        if (getCashPrior() < vars.redeemAmount) {
            return fail(Error.TOKEN_INSUFFICIENT_CASH, FailureInfo.REDEEM_TRANSFER_OUT_NOT_POSSIBLE);
        }

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        /*
         * We invoke doTransferOut for the redeemer and the redeemAmount.
         *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
         *  On success, the cToken has redeemAmount less of cash.
         *  If doTransferOut fails despite the fact we checked pre-conditions,
         *   we revert because we can't be sure if side effects occurred.
         */
        vars.err = doTransferOut(redeemer, vars.redeemAmount);
        require(vars.err == Error.NO_ERROR, "redeem transfer out failed");

        /* We write previously calculated values into storage */
        totalSupply = vars.totalSupplyNew;
        accountTokens[redeemer] = vars.accountTokensNew;

        /* We emit a Transfer event, and a Redeem event */
        emit Transfer(redeemer, address(this), vars.redeemTokens);
        emit Redeem(redeemer, vars.redeemAmount, vars.redeemTokens);

        /* We call the defense hook */
        comptroller.redeemVerify(address(this), redeemer, vars.redeemAmount, vars.redeemTokens);

        return uint(Error.NO_ERROR);
    }

    /**
      * @notice Sender borrows assets from the protocol to their own address
      * @param borrowAmount The amount of the underlying asset to borrow
      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
      */
    function borrowInternal(uint borrowAmount) internal nonReentrant returns (uint) {
        uint error = accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
            return fail(Error(error), FailureInfo.BORROW_ACCRUE_INTEREST_FAILED);
        }
        // borrowFresh emits borrow-specific logs on errors, so we don't need to
        return borrowFresh(msg.sender, borrowAmount);
    }

    struct BorrowLocalVars {
        Error err;
        MathError mathErr;
        uint accountBorrows;
        uint accountBorrowsNew;
        uint totalBorrowsNew;
    }

    /**
      * @notice Users borrow assets from the protocol to their own address
      * @param borrowAmount The amount of the underlying asset to borrow
      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
      */
    function borrowFresh(address payable borrower, uint borrowAmount) internal returns (uint) {
        /* Fail if borrow not allowed */
        uint allowed = comptroller.borrowAllowed(address(this), borrower, borrowAmount);
        if (allowed != 0) {
            return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.BORROW_COMPTROLLER_REJECTION, allowed);
        }

        /* Verify market's block number equals current block number */
        if (accrualBlockNumber != getBlockNumber()) {
            return fail(Error.MARKET_NOT_FRESH, FailureInfo.BORROW_FRESHNESS_CHECK);
        }

        /* Fail gracefully if protocol has insufficient underlying cash */
        if (getCashPrior() < borrowAmount) {
            return fail(Error.TOKEN_INSUFFICIENT_CASH, FailureInfo.BORROW_CASH_NOT_AVAILABLE);
        }

        BorrowLocalVars memory vars;

        /*
         * We calculate the new borrower and total borrow balances, failing on overflow:
         *  accountBorrowsNew = accountBorrows + borrowAmount
         *  totalBorrowsNew = totalBorrows + borrowAmount
         */
        (vars.mathErr, vars.accountBorrows) = borrowBalanceStoredInternal(borrower);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
        }

        (vars.mathErr, vars.accountBorrowsNew) = addUInt(vars.accountBorrows, borrowAmount);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
        }

        (vars.mathErr, vars.totalBorrowsNew) = addUInt(totalBorrows, borrowAmount);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
        }

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        /*
         * We invoke doTransferOut for the borrower and the borrowAmount.
         *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
         *  On success, the cToken borrowAmount less of cash.
         *  If doTransferOut fails despite the fact we checked pre-conditions,
         *   we revert because we can't be sure if side effects occurred.
         */
        vars.err = doTransferOut(borrower, borrowAmount);
        require(vars.err == Error.NO_ERROR, "borrow transfer out failed");

        /* We write the previously calculated values into storage */
        accountBorrows[borrower].principal = vars.accountBorrowsNew;
        accountBorrows[borrower].interestIndex = borrowIndex;
        totalBorrows = vars.totalBorrowsNew;

        /* We emit a Borrow event */
        emit Borrow(borrower, borrowAmount, vars.accountBorrowsNew, vars.totalBorrowsNew);

        /* We call the defense hook */
        comptroller.borrowVerify(address(this), borrower, borrowAmount);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Sender repays their own borrow
     * @param repayAmount The amount to repay
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function repayBorrowInternal(uint repayAmount) internal nonReentrant returns (uint) {
        uint error = accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
            return fail(Error(error), FailureInfo.REPAY_BORROW_ACCRUE_INTEREST_FAILED);
        }
        // repayBorrowFresh emits repay-borrow-specific logs on errors, so we don't need to
        return repayBorrowFresh(msg.sender, msg.sender, repayAmount);
    }

    /**
     * @notice Sender repays a borrow belonging to borrower
     * @param borrower the account with the debt being payed off
     * @param repayAmount The amount to repay
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function repayBorrowBehalfInternal(address borrower, uint repayAmount) internal nonReentrant returns (uint) {
        uint error = accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
            return fail(Error(error), FailureInfo.REPAY_BEHALF_ACCRUE_INTEREST_FAILED);
        }
        // repayBorrowFresh emits repay-borrow-specific logs on errors, so we don't need to
        return repayBorrowFresh(msg.sender, borrower, repayAmount);
    }

    struct RepayBorrowLocalVars {
        Error err;
        MathError mathErr;
        uint repayAmount;
        uint borrowerIndex;
        uint accountBorrows;
        uint accountBorrowsNew;
        uint totalBorrowsNew;
    }

    /**
     * @notice Borrows are repaid by another user (possibly the borrower).
     * @param payer the account paying off the borrow
     * @param borrower the account with the debt being payed off
     * @param repayAmount the amount of undelrying tokens being returned
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function repayBorrowFresh(address payer, address borrower, uint repayAmount) internal returns (uint) {
        /* Fail if repayBorrow not allowed */
        uint allowed = comptroller.repayBorrowAllowed(address(this), payer, borrower, repayAmount);
        if (allowed != 0) {
            return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.REPAY_BORROW_COMPTROLLER_REJECTION, allowed);
        }

        /* Verify market's block number equals current block number */
        if (accrualBlockNumber != getBlockNumber()) {
            return fail(Error.MARKET_NOT_FRESH, FailureInfo.REPAY_BORROW_FRESHNESS_CHECK);
        }

        RepayBorrowLocalVars memory vars;

        /* We remember the original borrowerIndex for verification purposes */
        vars.borrowerIndex = accountBorrows[borrower].interestIndex;

        /* We fetch the amount the borrower owes, with accumulated interest */
        (vars.mathErr, vars.accountBorrows) = borrowBalanceStoredInternal(borrower);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.REPAY_BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
        }

        /* If repayAmount == -1, repayAmount = accountBorrows */
        if (repayAmount == uint(-1)) {
            vars.repayAmount = vars.accountBorrows;
        } else {
            vars.repayAmount = repayAmount;
        }

        /* Fail if checkTransferIn fails */
        vars.err = checkTransferIn(payer, vars.repayAmount);
        if (vars.err != Error.NO_ERROR) {
            return fail(vars.err, FailureInfo.REPAY_BORROW_TRANSFER_IN_NOT_POSSIBLE);
        }

        /*
         * We calculate the new borrower and total borrow balances, failing on underflow:
         *  accountBorrowsNew = accountBorrows - repayAmount
         *  totalBorrowsNew = totalBorrows - repayAmount
         */
        (vars.mathErr, vars.accountBorrowsNew) = subUInt(vars.accountBorrows, vars.repayAmount);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.REPAY_BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
        }

        (vars.mathErr, vars.totalBorrowsNew) = subUInt(totalBorrows, vars.repayAmount);
        if (vars.mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.REPAY_BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
        }

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        /*
         * We call doTransferIn for the payer and the repayAmount
         *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
         *  On success, the cToken holds an additional repayAmount of cash.
         *  If doTransferIn fails despite the fact we checked pre-conditions,
         *   we revert because we can't be sure if side effects occurred.
         */
        vars.err = doTransferIn(payer, vars.repayAmount);
        require(vars.err == Error.NO_ERROR, "repay borrow transfer in failed");

        /* We write the previously calculated values into storage */
        accountBorrows[borrower].principal = vars.accountBorrowsNew;
        accountBorrows[borrower].interestIndex = borrowIndex;
        totalBorrows = vars.totalBorrowsNew;

        /* We emit a RepayBorrow event */
        emit RepayBorrow(payer, borrower, vars.repayAmount, vars.accountBorrowsNew, vars.totalBorrowsNew);

        /* We call the defense hook */
        comptroller.repayBorrowVerify(address(this), payer, borrower, vars.repayAmount, vars.borrowerIndex);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice The sender liquidates the borrowers collateral.
     *  The collateral seized is transferred to the liquidator.
     * @param borrower The borrower of this cToken to be liquidated
     * @param cTokenCollateral The market in which to seize collateral from the borrower
     * @param repayAmount The amount of the underlying borrowed asset to repay
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function liquidateBorrowInternal(address borrower, uint repayAmount, CToken cTokenCollateral) internal nonReentrant returns (uint) {
        uint error = accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted liquidation failed
            return fail(Error(error), FailureInfo.LIQUIDATE_ACCRUE_BORROW_INTEREST_FAILED);
        }

        error = cTokenCollateral.accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted liquidation failed
            return fail(Error(error), FailureInfo.LIQUIDATE_ACCRUE_COLLATERAL_INTEREST_FAILED);
        }

        // liquidateBorrowFresh emits borrow-specific logs on errors, so we don't need to
        return liquidateBorrowFresh(msg.sender, borrower, repayAmount, cTokenCollateral);
    }

    /**
     * @notice The liquidator liquidates the borrowers collateral.
     *  The collateral seized is transferred to the liquidator.
     * @param borrower The borrower of this cToken to be liquidated
     * @param liquidator The address repaying the borrow and seizing collateral
     * @param cTokenCollateral The market in which to seize collateral from the borrower
     * @param repayAmount The amount of the underlying borrowed asset to repay
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function liquidateBorrowFresh(address liquidator, address borrower, uint repayAmount, CToken cTokenCollateral) internal returns (uint) {
        /* Fail if liquidate not allowed */
        uint allowed = comptroller.liquidateBorrowAllowed(address(this), address(cTokenCollateral), liquidator, borrower, repayAmount);
        if (allowed != 0) {
            return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.LIQUIDATE_COMPTROLLER_REJECTION, allowed);
        }

        /* Verify market's block number equals current block number */
        if (accrualBlockNumber != getBlockNumber()) {
            return fail(Error.MARKET_NOT_FRESH, FailureInfo.LIQUIDATE_FRESHNESS_CHECK);
        }

        /* Verify cTokenCollateral market's block number equals current block number */
        if (cTokenCollateral.accrualBlockNumber() != getBlockNumber()) {
            return fail(Error.MARKET_NOT_FRESH, FailureInfo.LIQUIDATE_COLLATERAL_FRESHNESS_CHECK);
        }

        /* Fail if borrower = liquidator */
        if (borrower == liquidator) {
            return fail(Error.INVALID_ACCOUNT_PAIR, FailureInfo.LIQUIDATE_LIQUIDATOR_IS_BORROWER);
        }

        /* Fail if repayAmount = 0 */
        if (repayAmount == 0) {
            return fail(Error.INVALID_CLOSE_AMOUNT_REQUESTED, FailureInfo.LIQUIDATE_CLOSE_AMOUNT_IS_ZERO);
        }

        /* Fail if repayAmount = -1 */
        if (repayAmount == uint(-1)) {
            return fail(Error.INVALID_CLOSE_AMOUNT_REQUESTED, FailureInfo.LIQUIDATE_CLOSE_AMOUNT_IS_UINT_MAX);
        }

        /* We calculate the number of collateral tokens that will be seized */
        (uint amountSeizeError, uint seizeTokens) = comptroller.liquidateCalculateSeizeTokens(address(this), address(cTokenCollateral), repayAmount);
        if (amountSeizeError != 0) {
            return failOpaque(Error.COMPTROLLER_CALCULATION_ERROR, FailureInfo.LIQUIDATE_COMPTROLLER_CALCULATE_AMOUNT_SEIZE_FAILED, amountSeizeError);
        }

        /* Fail if seizeTokens > borrower collateral token balance */
        if (seizeTokens > cTokenCollateral.balanceOf(borrower)) {
            return fail(Error.TOKEN_INSUFFICIENT_BALANCE, FailureInfo.LIQUIDATE_SEIZE_TOO_MUCH);
        }

        /* Fail if repayBorrow fails */
        uint repayBorrowError = repayBorrowFresh(liquidator, borrower, repayAmount);
        if (repayBorrowError != uint(Error.NO_ERROR)) {
            return fail(Error(repayBorrowError), FailureInfo.LIQUIDATE_REPAY_BORROW_FRESH_FAILED);
        }

        /* Revert if seize tokens fails (since we cannot be sure of side effects) */
        uint seizeError = cTokenCollateral.seize(liquidator, borrower, seizeTokens);
        require(seizeError == uint(Error.NO_ERROR), "token seizure failed");

        /* We emit a LiquidateBorrow event */
        emit LiquidateBorrow(liquidator, borrower, repayAmount, address(cTokenCollateral), seizeTokens);

        /* We call the defense hook */
        comptroller.liquidateBorrowVerify(address(this), address(cTokenCollateral), liquidator, borrower, repayAmount, seizeTokens);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Transfers collateral tokens (this market) to the liquidator.
     * @dev Will fail unless called by another cToken during the process of liquidation.
     *  Its absolutely critical to use msg.sender as the borrowed cToken and not a parameter.
     * @param liquidator The account receiving seized collateral
     * @param borrower The account having collateral seized
     * @param seizeTokens The number of cTokens to seize
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function seize(address liquidator, address borrower, uint seizeTokens) external nonReentrant returns (uint) {
        /* Fail if seize not allowed */
        uint allowed = comptroller.seizeAllowed(address(this), msg.sender, liquidator, borrower, seizeTokens);
        if (allowed != 0) {
            return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.LIQUIDATE_SEIZE_COMPTROLLER_REJECTION, allowed);
        }

        /* Fail if borrower = liquidator */
        if (borrower == liquidator) {
            return fail(Error.INVALID_ACCOUNT_PAIR, FailureInfo.LIQUIDATE_SEIZE_LIQUIDATOR_IS_BORROWER);
        }

        MathError mathErr;
        uint borrowerTokensNew;
        uint liquidatorTokensNew;

        /*
         * We calculate the new borrower and liquidator token balances, failing on underflow/overflow:
         *  borrowerTokensNew = accountTokens[borrower] - seizeTokens
         *  liquidatorTokensNew = accountTokens[liquidator] + seizeTokens
         */
        (mathErr, borrowerTokensNew) = subUInt(accountTokens[borrower], seizeTokens);
        if (mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.LIQUIDATE_SEIZE_BALANCE_DECREMENT_FAILED, uint(mathErr));
        }

        (mathErr, liquidatorTokensNew) = addUInt(accountTokens[liquidator], seizeTokens);
        if (mathErr != MathError.NO_ERROR) {
            return failOpaque(Error.MATH_ERROR, FailureInfo.LIQUIDATE_SEIZE_BALANCE_INCREMENT_FAILED, uint(mathErr));
        }

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        /* We write the previously calculated values into storage */
        accountTokens[borrower] = borrowerTokensNew;
        accountTokens[liquidator] = liquidatorTokensNew;

        /* Emit a Transfer event */
        emit Transfer(borrower, liquidator, seizeTokens);

        /* We call the defense hook */
        comptroller.seizeVerify(address(this), msg.sender, liquidator, borrower, seizeTokens);

        return uint(Error.NO_ERROR);
    }


    /*** Admin Functions ***/

    /**
      * @notice Begins transfer of admin rights. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
      * @dev Admin function to begin change of admin. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
      * @param newPendingAdmin New pending admin.
      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
      *
      * TODO: Should we add a second arg to verify, like a checksum of `newAdmin` address?
      */
    function _setPendingAdmin(address payable newPendingAdmin) external returns (uint) {
        // Check caller = admin
        if (msg.sender != admin) {
            return fail(Error.UNAUTHORIZED, FailureInfo.SET_PENDING_ADMIN_OWNER_CHECK);
        }

        // Save current value, if any, for inclusion in log
        address oldPendingAdmin = pendingAdmin;

        // Store pendingAdmin with value newPendingAdmin
        pendingAdmin = newPendingAdmin;

        // Emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin)
        emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin);

        return uint(Error.NO_ERROR);
    }

    /**
      * @notice Accepts transfer of admin rights. msg.sender must be pendingAdmin
      * @dev Admin function for pending admin to accept role and update admin
      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
      */
    function _acceptAdmin() external returns (uint) {
        // Check caller is pendingAdmin and pendingAdmin ≠ address(0)
        if (msg.sender != pendingAdmin || msg.sender == address(0)) {
            return fail(Error.UNAUTHORIZED, FailureInfo.ACCEPT_ADMIN_PENDING_ADMIN_CHECK);
        }

        // Save current values for inclusion in log
        address oldAdmin = admin;
        address oldPendingAdmin = pendingAdmin;

        // Store admin with value pendingAdmin
        admin = pendingAdmin;

        // Clear the pending value
        pendingAdmin = address(0);

        emit NewAdmin(oldAdmin, admin);
        emit NewPendingAdmin(oldPendingAdmin, pendingAdmin);

        return uint(Error.NO_ERROR);
    }

    /**
      * @notice Sets a new comptroller for the market
      * @dev Admin function to set a new comptroller
      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
      */
    function _setComptroller(ComptrollerInterface newComptroller) public returns (uint) {
        // Check caller is admin
        if (msg.sender != admin) {
            return fail(Error.UNAUTHORIZED, FailureInfo.SET_COMPTROLLER_OWNER_CHECK);
        }

        ComptrollerInterface oldComptroller = comptroller;
        // Ensure invoke comptroller.isComptroller() returns true
        require(newComptroller.isComptroller(), "marker method returned false");

        // Set market's comptroller to newComptroller
        comptroller = newComptroller;

        // Emit NewComptroller(oldComptroller, newComptroller)
        emit NewComptroller(oldComptroller, newComptroller);

        return uint(Error.NO_ERROR);
    }

    /**
      * @notice accrues interest and sets a new reserve factor for the protocol using _setReserveFactorFresh
      * @dev Admin function to accrue interest and set a new reserve factor
      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
      */
    function _setReserveFactor(uint newReserveFactorMantissa) external nonReentrant returns (uint) {
        uint error = accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted reserve factor change failed.
            return fail(Error(error), FailureInfo.SET_RESERVE_FACTOR_ACCRUE_INTEREST_FAILED);
        }
        // _setReserveFactorFresh emits reserve-factor-specific logs on errors, so we don't need to.
        return _setReserveFactorFresh(newReserveFactorMantissa);
    }

    /**
      * @notice Sets a new reserve factor for the protocol (*requires fresh interest accrual)
      * @dev Admin function to set a new reserve factor
      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
      */
    function _setReserveFactorFresh(uint newReserveFactorMantissa) internal returns (uint) {
        // Check caller is admin
        if (msg.sender != admin) {
            return fail(Error.UNAUTHORIZED, FailureInfo.SET_RESERVE_FACTOR_ADMIN_CHECK);
        }

        // Verify market's block number equals current block number
        if (accrualBlockNumber != getBlockNumber()) {
            // TODO: static_assert + no error code?
            return fail(Error.MARKET_NOT_FRESH, FailureInfo.SET_RESERVE_FACTOR_FRESH_CHECK);
        }

        // Check newReserveFactor ≤ maxReserveFactor
        if (newReserveFactorMantissa > reserveFactorMaxMantissa) {
            return fail(Error.BAD_INPUT, FailureInfo.SET_RESERVE_FACTOR_BOUNDS_CHECK);
        }

        uint oldReserveFactorMantissa = reserveFactorMantissa;
        reserveFactorMantissa = newReserveFactorMantissa;

        emit NewReserveFactor(oldReserveFactorMantissa, newReserveFactorMantissa);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Accrues interest and reduces reserves by transferring to admin
     * @param reduceAmount Amount of reduction to reserves
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _reduceReserves(uint reduceAmount) external nonReentrant returns (uint) {
        uint error = accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted reduce reserves failed.
            return fail(Error(error), FailureInfo.REDUCE_RESERVES_ACCRUE_INTEREST_FAILED);
        }
        // _reduceReservesFresh emits reserve-reduction-specific logs on errors, so we don't need to.
        return _reduceReservesFresh(reduceAmount);
    }

    /**
     * @notice Reduces reserves by transferring to admin
     * @dev Requires fresh interest accrual
     * @param reduceAmount Amount of reduction to reserves
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _reduceReservesFresh(uint reduceAmount) internal returns (uint) {
        Error err;
        // totalReserves - reduceAmount
        uint totalReservesNew;

        // Check caller is admin
        if (msg.sender != admin) {
            return fail(Error.UNAUTHORIZED, FailureInfo.REDUCE_RESERVES_ADMIN_CHECK);
        }

        // We fail gracefully unless market's block number equals current block number
        if (accrualBlockNumber != getBlockNumber()) {
            // TODO: static_assert + no error code?
            return fail(Error.MARKET_NOT_FRESH, FailureInfo.REDUCE_RESERVES_FRESH_CHECK);
        }

        // Fail gracefully if protocol has insufficient underlying cash
        if (getCashPrior() < reduceAmount) {
            return fail(Error.TOKEN_INSUFFICIENT_CASH, FailureInfo.REDUCE_RESERVES_CASH_NOT_AVAILABLE);
        }

        // Check reduceAmount ≤ reserves[n] (totalReserves)
        // TODO: I'm following the spec literally here but I think we should we just use SafeMath instead and fail on an error (which would be underflow)
        if (reduceAmount > totalReserves) {
            return fail(Error.BAD_INPUT, FailureInfo.REDUCE_RESERVES_VALIDATION);
        }

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        totalReservesNew = totalReserves - reduceAmount;
        // We checked reduceAmount <= totalReserves above, so this should never revert.
        require(totalReservesNew <= totalReserves, "reduce reserves unexpected underflow");

        // Store reserves[n+1] = reserves[n] - reduceAmount
        totalReserves = totalReservesNew;

        // invoke doTransferOut(reduceAmount, admin)
        err = doTransferOut(admin, reduceAmount);
        // we revert on the failure of this command
        require(err == Error.NO_ERROR, "reduce reserves transfer out failed");

        emit ReservesReduced(admin, reduceAmount, totalReservesNew);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice accrues interest and updates the interest rate model using _setInterestRateModelFresh
     * @dev Admin function to accrue interest and update the interest rate model
     * @param newInterestRateModel the new interest rate model to use
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _setInterestRateModel(InterestRateModel newInterestRateModel) public returns (uint) {
        uint error = accrueInterest();
        if (error != uint(Error.NO_ERROR)) {
            // accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted change of interest rate model failed
            return fail(Error(error), FailureInfo.SET_INTEREST_RATE_MODEL_ACCRUE_INTEREST_FAILED);
        }
        // _setInterestRateModelFresh emits interest-rate-model-update-specific logs on errors, so we don't need to.
        return _setInterestRateModelFresh(newInterestRateModel);
    }

    /**
     * @notice updates the interest rate model (*requires fresh interest accrual)
     * @dev Admin function to update the interest rate model
     * @param newInterestRateModel the new interest rate model to use
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _setInterestRateModelFresh(InterestRateModel newInterestRateModel) internal returns (uint) {

        // Used to store old model for use in the event that is emitted on success
        InterestRateModel oldInterestRateModel;

        // Check caller is admin
        if (msg.sender != admin) {
            return fail(Error.UNAUTHORIZED, FailureInfo.SET_INTEREST_RATE_MODEL_OWNER_CHECK);
        }

        // We fail gracefully unless market's block number equals current block number
        if (accrualBlockNumber != getBlockNumber()) {
            // TODO: static_assert + no error code?
            return fail(Error.MARKET_NOT_FRESH, FailureInfo.SET_INTEREST_RATE_MODEL_FRESH_CHECK);
        }

        // Track the market's current interest rate model
        oldInterestRateModel = interestRateModel;

        // Ensure invoke newInterestRateModel.isInterestRateModel() returns true
        require(newInterestRateModel.isInterestRateModel(), "marker method returned false");

        // Set the interest rate model to newInterestRateModel
        interestRateModel = newInterestRateModel;

        // Emit NewMarketInterestRateModel(oldInterestRateModel, newInterestRateModel)
        emit NewMarketInterestRateModel(oldInterestRateModel, newInterestRateModel);

        return uint(Error.NO_ERROR);
    }

    /*** Safe Token ***/

    /**
     * @notice Gets balance of this contract in terms of the underlying
     * @dev This excludes the value of the current message, if any
     * @return The quantity of underlying owned by this contract
     */
    function getCashPrior() internal view returns (uint);

    /**
     * @dev Checks whether or not there is sufficient allowance for this contract to move amount from `from` and
     *      whether or not `from` has a balance of at least `amount`. Does NOT do a transfer.
     */
    function checkTransferIn(address from, uint amount) internal view returns (Error);

    /**
     * @dev Performs a transfer in, ideally returning an explanatory error code upon failure rather than reverting.
     *  If caller has not called `checkTransferIn`, this may revert due to insufficient balance or insufficient allowance.
     *  If caller has called `checkTransferIn` successfully, this should not revert in normal conditions.
     */
    function doTransferIn(address from, uint amount) internal returns (Error);

    /**
     * @dev Performs a transfer out, ideally returning an explanatory error code upon failure tather than reverting.
     *  If caller has not called checked protocol's balance, may revert due to insufficient cash held in the contract.
     *  If caller has checked protocol's balance, and verified it is >= amount, this should not revert in normal conditions.
     */
    function doTransferOut(address payable to, uint amount) internal returns (Error);
}

// File: contracts/PriceOracle.sol

pragma solidity ^0.5.8;


interface PriceOracle {
    /**
     * @notice Indicator that this is a PriceOracle contract (for inspection)
     */
    function isPriceOracle() external pure returns (bool);

    /**
      * @notice Get the underlying price of a cToken asset
      * @param cToken The cToken to get the underlying price of
      * @return The underlying asset price mantissa (scaled by 1e18).
      *  Zero means the price is unavailable.
      */
    function getUnderlyingPrice(CToken cToken) external view returns (uint);
}

// File: contracts/ComptrollerStorage.sol

pragma solidity ^0.5.8;



contract UnitrollerAdminStorage {
    /**
    * @notice Administrator for this contract
    */
    address public admin;

    /**
    * @notice Pending administrator for this contract
    */
    address public pendingAdmin;

    /**
    * @notice Active brains of Unitroller
    */
    address public comptrollerImplementation;

    /**
    * @notice Pending brains of Unitroller
    */
    address public pendingComptrollerImplementation;
}

contract ComptrollerV1Storage is UnitrollerAdminStorage {

    /**
     * @notice Oracle which gives the price of any given asset
     */
    PriceOracle public oracle;

    /**
     * @notice Multiplier used to calculate the maximum repayAmount when liquidating a borrow
     */
    uint public closeFactorMantissa;

    /**
     * @notice Multiplier representing the discount on collateral that a liquidator receives
     */
    uint public liquidationIncentiveMantissa;

    /**
     * @notice Max number of assets a single account can participate in (borrow or use as collateral)
     */
    uint public maxAssets;

    /**
     * @notice Per-account mapping of "assets you are in", capped by maxAssets
     */
    mapping(address => CToken[]) public accountAssets;

}

// File: contracts/Unitroller.sol

pragma solidity ^0.5.8;


/**
 * @title ComptrollerCore
 * @dev storage for the comptroller will be at this address, and
 * cTokens should reference this contract rather than a deployed implementation if
 *
 */
contract Unitroller is UnitrollerAdminStorage, ComptrollerErrorReporter {

    /**
      * @notice Emitted when pendingComptrollerImplementation is changed
      */
    event NewPendingImplementation(address oldPendingImplementation, address newPendingImplementation);

    /**
      * @notice Emitted when pendingComptrollerImplementation is accepted, which means comptroller implementation is updated
      */
    event NewImplementation(address oldImplementation, address newImplementation);

    /**
      * @notice Emitted when pendingAdmin is changed
      */
    event NewPendingAdmin(address oldPendingAdmin, address newPendingAdmin);

    /**
      * @notice Emitted when pendingAdmin is accepted, which means admin is updated
      */
    event NewAdmin(address oldAdmin, address newAdmin);

    constructor() public {
        // Set admin to caller
        admin = msg.sender;
    }

    /*** Admin Functions ***/
    function _setPendingImplementation(address newPendingImplementation) public returns (uint) {

        if (msg.sender != admin) {
            return fail(Error.UNAUTHORIZED, FailureInfo.SET_PENDING_IMPLEMENTATION_OWNER_CHECK);
        }

        address oldPendingImplementation = pendingComptrollerImplementation;

        pendingComptrollerImplementation = newPendingImplementation;

        emit NewPendingImplementation(oldPendingImplementation, pendingComptrollerImplementation);

        return uint(Error.NO_ERROR);
    }

    /**
    * @notice Accepts new implementation of comptroller. msg.sender must be pendingImplementation
    * @dev Admin function for new implementation to accept it's role as implementation
    * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
    */
    function _acceptImplementation() public returns (uint) {
        // Check caller is pendingImplementation and pendingImplementation ≠ address(0)
        if (msg.sender != pendingComptrollerImplementation || pendingComptrollerImplementation == address(0)) {
            return fail(Error.UNAUTHORIZED, FailureInfo.ACCEPT_PENDING_IMPLEMENTATION_ADDRESS_CHECK);
        }

        // Save current values for inclusion in log
        address oldImplementation = comptrollerImplementation;
        address oldPendingImplementation = pendingComptrollerImplementation;

        comptrollerImplementation = pendingComptrollerImplementation;

        pendingComptrollerImplementation = address(0);

        emit NewImplementation(oldImplementation, comptrollerImplementation);
        emit NewPendingImplementation(oldPendingImplementation, pendingComptrollerImplementation);

        return uint(Error.NO_ERROR);
    }


    /**
      * @notice Begins transfer of admin rights. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
      * @dev Admin function to begin change of admin. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
      * @param newPendingAdmin New pending admin.
      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
      *
      * TODO: Should we add a second arg to verify, like a checksum of `newAdmin` address?
      */
    function _setPendingAdmin(address newPendingAdmin) public returns (uint) {
        // Check caller = admin
        if (msg.sender != admin) {
            return fail(Error.UNAUTHORIZED, FailureInfo.SET_PENDING_ADMIN_OWNER_CHECK);
        }

        // Save current value, if any, for inclusion in log
        address oldPendingAdmin = pendingAdmin;

        // Store pendingAdmin with value newPendingAdmin
        pendingAdmin = newPendingAdmin;

        // Emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin)
        emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin);

        return uint(Error.NO_ERROR);
    }

    /**
      * @notice Accepts transfer of admin rights. msg.sender must be pendingAdmin
      * @dev Admin function for pending admin to accept role and update admin
      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
      */
    function _acceptAdmin() public returns (uint) {
        // Check caller is pendingAdmin and pendingAdmin ≠ address(0)
        if (msg.sender != pendingAdmin || msg.sender == address(0)) {
            return fail(Error.UNAUTHORIZED, FailureInfo.ACCEPT_ADMIN_PENDING_ADMIN_CHECK);
        }

        // Save current values for inclusion in log
        address oldAdmin = admin;
        address oldPendingAdmin = pendingAdmin;

        // Store admin with value pendingAdmin
        admin = pendingAdmin;

        // Clear the pending value
        pendingAdmin = address(0);

        emit NewAdmin(oldAdmin, admin);
        emit NewPendingAdmin(oldPendingAdmin, pendingAdmin);

        return uint(Error.NO_ERROR);
    }

    /**
     * @dev Delegates execution to an implementation contract.
     * It returns to the external caller whatever the implementation returns
     * or forwards reverts.
     */
    function () payable external {
        // delegate all other functions to current implementation
        (bool success, ) = comptrollerImplementation.delegatecall(msg.data);

        // solium-disable-next-line security/no-inline-assembly
        assembly {
              let free_mem_ptr := mload(0x40)
              returndatacopy(free_mem_ptr, 0, returndatasize)

              switch success
              case 0 { revert(free_mem_ptr, returndatasize) }
              default { return(free_mem_ptr, returndatasize) }
        }
    }
}

{"CarefulMath.sol":{"content":"pragma solidity ^0.5.8;\n\n/**\n  * @title Careful Math\n  * @author Compound\n  * @notice Derived from OpenZeppelin\u0027s SafeMath library\n  *         https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/contracts/math/SafeMath.sol\n  */\ncontract CarefulMath {\n\n    /**\n     * @dev Possible error codes that we can return\n     */\n    enum MathError {\n        NO_ERROR,\n        DIVISION_BY_ZERO,\n        INTEGER_OVERFLOW,\n        INTEGER_UNDERFLOW\n    }\n\n    /**\n    * @dev Multiplies two numbers, returns an error on overflow.\n    */\n    function mulUInt(uint a, uint b) internal pure returns (MathError, uint) {\n        if (a == 0) {\n            return (MathError.NO_ERROR, 0);\n        }\n\n        uint c = a * b;\n\n        if (c / a != b) {\n            return (MathError.INTEGER_OVERFLOW, 0);\n        } else {\n            return (MathError.NO_ERROR, c);\n        }\n    }\n\n    /**\n    * @dev Integer division of two numbers, truncating the quotient.\n    */\n    function divUInt(uint a, uint b) internal pure returns (MathError, uint) {\n        if (b == 0) {\n            return (MathError.DIVISION_BY_ZERO, 0);\n        }\n\n        return (MathError.NO_ERROR, a / b);\n    }\n\n    /**\n    * @dev Subtracts two numbers, returns an error on overflow (i.e. if subtrahend is greater than minuend).\n    */\n    function subUInt(uint a, uint b) internal pure returns (MathError, uint) {\n        if (b \u003c= a) {\n            return (MathError.NO_ERROR, a - b);\n        } else {\n            return (MathError.INTEGER_UNDERFLOW, 0);\n        }\n    }\n\n    /**\n    * @dev Adds two numbers, returns an error on overflow.\n    */\n    function addUInt(uint a, uint b) internal pure returns (MathError, uint) {\n        uint c = a + b;\n\n        if (c \u003e= a) {\n            return (MathError.NO_ERROR, c);\n        } else {\n            return (MathError.INTEGER_OVERFLOW, 0);\n        }\n    }\n\n    /**\n    * @dev add a and b and then subtract c\n    */\n    function addThenSubUInt(uint a, uint b, uint c) internal pure returns (MathError, uint) {\n        (MathError err0, uint sum) = addUInt(a, b);\n\n        if (err0 != MathError.NO_ERROR) {\n            return (err0, 0);\n        }\n\n        return subUInt(sum, c);\n    }\n}"},"CErc20.sol":{"content":"pragma solidity ^0.5.8;\n\nimport \"./CToken.sol\";\n\n/**\n * @title Compound\u0027s CErc20 Contract\n * @notice CTokens which wrap an EIP-20 underlying\n * @author Compound\n */\ncontract CErc20 is CToken {\n\n    /**\n     * @notice Underlying asset for this CToken\n     */\n    address public underlying;\n\n    /**\n     * @notice Construct a new money market\n     * @param underlying_ The address of the underlying asset\n     * @param comptroller_ The address of the Comptroller\n     * @param interestRateModel_ The address of the interest rate model\n     * @param initialExchangeRateMantissa_ The initial exchange rate, scaled by 1e18\n     * @param name_ ERC-20 name of this token\n     * @param symbol_ ERC-20 symbol of this token\n     * @param decimals_ ERC-20 decimal precision of this token\n     */\n    constructor(address underlying_,\n                ComptrollerInterface comptroller_,\n                InterestRateModel interestRateModel_,\n                uint initialExchangeRateMantissa_,\n                string memory name_,\n                string memory symbol_,\n                uint decimals_) public\n    CToken(comptroller_, interestRateModel_, initialExchangeRateMantissa_, name_, symbol_, decimals_) {\n        // Set underlying\n        underlying = underlying_;\n        EIP20Interface(underlying).totalSupply(); // Sanity check the underlying\n    }\n\n    /*** User Interface ***/\n\n    /**\n     * @notice Sender supplies assets into the market and receives cTokens in exchange\n     * @dev Accrues interest whether or not the operation succeeds, unless reverted\n     * @param mintAmount The amount of the underlying asset to supply\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function mint(uint mintAmount) external returns (uint) {\n        return mintInternal(mintAmount);\n    }\n\n    /**\n     * @notice Sender redeems cTokens in exchange for the underlying asset\n     * @dev Accrues interest whether or not the operation succeeds, unless reverted\n     * @param redeemTokens The number of cTokens to redeem into underlying\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function redeem(uint redeemTokens) external returns (uint) {\n        return redeemInternal(redeemTokens);\n    }\n\n    /**\n     * @notice Sender redeems cTokens in exchange for a specified amount of underlying asset\n     * @dev Accrues interest whether or not the operation succeeds, unless reverted\n     * @param redeemAmount The amount of underlying to redeem\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function redeemUnderlying(uint redeemAmount) external returns (uint) {\n        return redeemUnderlyingInternal(redeemAmount);\n    }\n\n    /**\n      * @notice Sender borrows assets from the protocol to their own address\n      * @param borrowAmount The amount of the underlying asset to borrow\n      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n      */\n    function borrow(uint borrowAmount) external returns (uint) {\n        return borrowInternal(borrowAmount);\n    }\n\n    /**\n     * @notice Sender repays their own borrow\n     * @param repayAmount The amount to repay\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function repayBorrow(uint repayAmount) external returns (uint) {\n        return repayBorrowInternal(repayAmount);\n    }\n\n    /**\n     * @notice Sender repays a borrow belonging to borrower\n     * @param borrower the account with the debt being payed off\n     * @param repayAmount The amount to repay\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function repayBorrowBehalf(address borrower, uint repayAmount) external returns (uint) {\n        return repayBorrowBehalfInternal(borrower, repayAmount);\n    }\n\n    /**\n     * @notice The sender liquidates the borrowers collateral.\n     *  The collateral seized is transferred to the liquidator.\n     * @param borrower The borrower of this cToken to be liquidated\n     * @param cTokenCollateral The market in which to seize collateral from the borrower\n     * @param repayAmount The amount of the underlying borrowed asset to repay\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function liquidateBorrow(address borrower, uint repayAmount, CToken cTokenCollateral) external returns (uint) {\n        return liquidateBorrowInternal(borrower, repayAmount, cTokenCollateral);\n    }\n\n    /*** Safe Token ***/\n\n    /**\n     * @notice Gets balance of this contract in terms of the underlying\n     * @dev This excludes the value of the current message, if any\n     * @return The quantity of underlying tokens owned by this contract\n     */\n    function getCashPrior() internal view returns (uint) {\n        EIP20Interface token = EIP20Interface(underlying);\n        return token.balanceOf(address(this));\n    }\n\n    /**\n     * @dev Checks whether or not there is sufficient allowance for this contract to move amount from `from` and\n     *      whether or not `from` has a balance of at least `amount`. Does NOT do a transfer.\n     */\n    function checkTransferIn(address from, uint amount) internal view returns (Error) {\n        EIP20Interface token = EIP20Interface(underlying);\n\n        if (token.allowance(from, address(this)) \u003c amount) {\n            return Error.TOKEN_INSUFFICIENT_ALLOWANCE;\n        }\n\n        if (token.balanceOf(from) \u003c amount) {\n            return Error.TOKEN_INSUFFICIENT_BALANCE;\n        }\n\n        return Error.NO_ERROR;\n    }\n\n    /**\n     * @dev Similar to EIP20 transfer, except it handles a False result from `transferFrom` and returns an explanatory\n     *      error code rather than reverting.  If caller has not called `checkTransferIn`, this may revert due to\n     *      insufficient balance or insufficient allowance. If caller has called `checkTransferIn` prior to this call,\n     *      and it returned Error.NO_ERROR, this should not revert in normal conditions.\n     *\n     *      Note: This wrapper safely handles non-standard ERC-20 tokens that do not return a value.\n     *            See here: https://medium.com/coinmonks/missing-return-value-bug-at-least-130-tokens-affected-d67bf08521ca\n     */\n    function doTransferIn(address from, uint amount) internal returns (Error) {\n        EIP20NonStandardInterface token = EIP20NonStandardInterface(underlying);\n        bool result;\n\n        token.transferFrom(from, address(this), amount);\n\n        // solium-disable-next-line security/no-inline-assembly\n        assembly {\n            switch returndatasize()\n                case 0 {                      // This is a non-standard ERC-20\n                    result := not(0)          // set result to true\n                }\n                case 32 {                     // This is a complaint ERC-20\n                    returndatacopy(0, 0, 32)\n                    result := mload(0)        // Set `result = returndata` of external call\n                }\n                default {                     // This is an excessively non-compliant ERC-20, revert.\n                    revert(0, 0)\n                }\n        }\n\n        if (!result) {\n            return Error.TOKEN_TRANSFER_IN_FAILED;\n        }\n\n        return Error.NO_ERROR;\n    }\n\n    /**\n     * @dev Similar to EIP20 transfer, except it handles a False result from `transfer` and returns an explanatory\n     *      error code rather than reverting. If caller has not called checked protocol\u0027s balance, this may revert due to\n     *      insufficient cash held in this contract. If caller has checked protocol\u0027s balance prior to this call, and verified\n     *      it is \u003e= amount, this should not revert in normal conditions.\n     *\n     *      Note: This wrapper safely handles non-standard ERC-20 tokens that do not return a value.\n     *            See here: https://medium.com/coinmonks/missing-return-value-bug-at-least-130-tokens-affected-d67bf08521ca\n     */\n    function doTransferOut(address payable to, uint amount) internal returns (Error) {\n        EIP20NonStandardInterface token = EIP20NonStandardInterface(underlying);\n        bool result;\n\n        token.transfer(to, amount);\n\n        // solium-disable-next-line security/no-inline-assembly\n        assembly {\n            switch returndatasize()\n                case 0 {                      // This is a non-standard ERC-20\n                    result := not(0)          // set result to true\n                }\n                case 32 {                     // This is a complaint ERC-20\n                    returndatacopy(0, 0, 32)\n                    result := mload(0)        // Set `result = returndata` of external call\n                }\n                default {                     // This is an excessively non-compliant ERC-20, revert.\n                    revert(0, 0)\n                }\n        }\n\n        if (!result) {\n            return Error.TOKEN_TRANSFER_OUT_FAILED;\n        }\n\n        return Error.NO_ERROR;\n    }\n}\n"},"CEther.sol":{"content":"pragma solidity ^0.5.8;\n\nimport \"./CToken.sol\";\n\n/**\n * @title Compound\u0027s CEther Contract\n * @notice CToken which wraps Ether\n * @author Compound\n */\ncontract CEther is CToken {\n    /**\n     * @notice Construct a new CEther money market\n     * @param comptroller_ The address of the Comptroller\n     * @param interestRateModel_ The address of the interest rate model\n     * @param initialExchangeRateMantissa_ The initial exchange rate, scaled by 1e18\n     * @param name_ ERC-20 name of this token\n     * @param symbol_ ERC-20 symbol of this token\n     * @param decimals_ ERC-20 decimal precision of this token\n     */\n    constructor(ComptrollerInterface comptroller_,\n                InterestRateModel interestRateModel_,\n                uint initialExchangeRateMantissa_,\n                string memory name_,\n                string memory symbol_,\n                uint decimals_) public\n    CToken(comptroller_, interestRateModel_, initialExchangeRateMantissa_, name_, symbol_, decimals_) {}\n\n    /*** User Interface ***/\n\n    /**\n     * @notice Sender supplies assets into the market and receives cTokens in exchange\n     * @dev Reverts upon any failure\n     */\n    function mint() external payable {\n        requireNoError(mintInternal(msg.value), \"mint failed\");\n    }\n\n    /**\n     * @notice Sender redeems cTokens in exchange for the underlying asset\n     * @dev Accrues interest whether or not the operation succeeds, unless reverted\n     * @param redeemTokens The number of cTokens to redeem into underlying\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function redeem(uint redeemTokens) external returns (uint) {\n        return redeemInternal(redeemTokens);\n    }\n\n    /**\n     * @notice Sender redeems cTokens in exchange for a specified amount of underlying asset\n     * @dev Accrues interest whether or not the operation succeeds, unless reverted\n     * @param redeemAmount The amount of underlying to redeem\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function redeemUnderlying(uint redeemAmount) external returns (uint) {\n        return redeemUnderlyingInternal(redeemAmount);\n    }\n\n    /**\n      * @notice Sender borrows assets from the protocol to their own address\n      * @param borrowAmount The amount of the underlying asset to borrow\n      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n      */\n    function borrow(uint borrowAmount) external returns (uint) {\n        return borrowInternal(borrowAmount);\n    }\n\n    /**\n     * @notice Sender repays their own borrow\n     * @dev Reverts upon any failure\n     */\n    function repayBorrow() external payable {\n        requireNoError(repayBorrowInternal(msg.value), \"repayBorrow failed\");\n    }\n\n    /**\n     * @notice Sender repays a borrow belonging to borrower\n     * @dev Reverts upon any failure\n     * @param borrower the account with the debt being payed off\n     */\n    function repayBorrowBehalf(address borrower) external payable {\n        requireNoError(repayBorrowBehalfInternal(borrower, msg.value), \"repayBorrowBehalf failed\");\n    }\n\n    /**\n     * @notice The sender liquidates the borrowers collateral.\n     *  The collateral seized is transferred to the liquidator.\n     * @dev Reverts upon any failure\n     * @param borrower The borrower of this cToken to be liquidated\n     * @param cTokenCollateral The market in which to seize collateral from the borrower\n     */\n    function liquidateBorrow(address borrower, CToken cTokenCollateral) external payable {\n        requireNoError(liquidateBorrowInternal(borrower, msg.value, cTokenCollateral), \"liquidateBorrow failed\");\n    }\n\n    /**\n     * @notice Send Ether to CEther to mint\n     */\n    function () external payable {\n        requireNoError(mintInternal(msg.value), \"mint failed\");\n    }\n\n    /*** Safe Token ***/\n\n    /**\n     * @notice Gets balance of this contract in terms of Ether, before this message\n     * @dev This excludes the value of the current message, if any\n     * @return The quantity of Ether owned by this contract\n     */\n    function getCashPrior() internal view returns (uint) {\n        (MathError err, uint startingBalance) = subUInt(address(this).balance, msg.value);\n        require(err == MathError.NO_ERROR);\n        return startingBalance;\n    }\n\n    /**\n     * @notice Checks whether the requested transfer matches the `msg`\n     * @dev Does NOT do a transfer\n     * @param from Address sending the Ether\n     * @param amount Amount of Ether being sent\n     * @return Whether or not the transfer checks out\n     */\n    function checkTransferIn(address from, uint amount) internal view returns (Error) {\n        // Sanity checks\n        require(msg.sender == from, \"sender mismatch\");\n        require(msg.value == amount, \"value mismatch\");\n        return Error.NO_ERROR;\n    }\n\n    /**\n     * @notice Perform the actual transfer in, which is a no-op\n     * @param from Address sending the Ether\n     * @param amount Amount of Ether being sent\n     * @return Success\n     */\n    function doTransferIn(address from, uint amount) internal returns (Error) {\n        // Sanity checks\n        require(msg.sender == from, \"sender mismatch\");\n        require(msg.value == amount, \"value mismatch\");\n        return Error.NO_ERROR;\n    }\n\n    function doTransferOut(address payable to, uint amount) internal returns (Error) {\n        /* Send the Ether, with minimal gas and revert on failure */\n        to.transfer(amount);\n        return Error.NO_ERROR;\n    }\n\n    function requireNoError(uint errCode, string memory message) internal pure {\n        if (errCode == uint(Error.NO_ERROR)) {\n            return;\n        }\n\n        bytes memory fullMessage = new bytes(bytes(message).length + 5);\n        uint i;\n\n        for (i = 0; i \u003c bytes(message).length; i++) {\n            fullMessage[i] = bytes(message)[i];\n        }\n\n        fullMessage[i+0] = byte(uint8(32));\n        fullMessage[i+1] = byte(uint8(40));\n        fullMessage[i+2] = byte(uint8(48 + ( errCode / 10 )));\n        fullMessage[i+3] = byte(uint8(48 + ( errCode % 10 )));\n        fullMessage[i+4] = byte(uint8(41));\n\n        require(errCode == uint(Error.NO_ERROR), string(fullMessage));\n    }\n}\n"},"Comptroller.sol":{"content":"pragma solidity ^0.5.8;\n\nimport \"./CToken.sol\";\nimport \"./ErrorReporter.sol\";\nimport \"./Exponential.sol\";\nimport \"./PriceOracle.sol\";\nimport \"./ComptrollerInterface.sol\";\nimport \"./ComptrollerStorage.sol\";\nimport \"./Unitroller.sol\";\n\n/**\n * @title Compound\u0027s Comptroller Contract\n * @author Compound\n */\ncontract Comptroller is ComptrollerV1Storage, ComptrollerInterface, ComptrollerErrorReporter, Exponential {\n    struct Market {\n        /**\n         * @notice Whether or not this market is listed\n         */\n        bool isListed;\n\n        /**\n         * @notice Multiplier representing the most one can borrow against their collateral in this market.\n         *  For instance, 0.9 to allow borrowing 90% of collateral value.\n         *  Must be between 0 and 1, and stored as a mantissa.\n         */\n        uint collateralFactorMantissa;\n\n        /**\n         * @notice Per-market mapping of \"accounts in this asset\"\n         */\n        mapping(address =\u003e bool) accountMembership;\n    }\n\n    /**\n     * @notice Official mapping of cTokens -\u003e Market metadata\n     * @dev Used e.g. to determine if a market is supported\n     */\n    mapping(address =\u003e Market) public markets;\n\n    /**\n     * @notice Emitted when an admin supports a market\n     */\n    event MarketListed(CToken cToken);\n\n    /**\n     * @notice Emitted when an account enters a market\n     */\n    event MarketEntered(CToken cToken, address account);\n\n    /**\n     * @notice Emitted when an account exits a market\n     */\n    event MarketExited(CToken cToken, address account);\n\n    /**\n     * @notice Emitted when close factor is changed by admin\n     */\n    event NewCloseFactor(uint oldCloseFactorMantissa, uint newCloseFactorMantissa);\n\n    /**\n     * @notice Emitted when a collateral factor is changed by admin\n     */\n    event NewCollateralFactor(CToken cToken, uint oldCollateralFactorMantissa, uint newCollateralFactorMantissa);\n\n    /**\n     * @notice Emitted when liquidation incentive is changed by admin\n     */\n    event NewLiquidationIncentive(uint oldLiquidationIncentiveMantissa, uint newLiquidationIncentiveMantissa);\n\n    /**\n     * @notice Emitted when maxAssets is changed by admin\n     */\n    event NewMaxAssets(uint oldMaxAssets, uint newMaxAssets);\n\n    /**\n     * @notice Emitted when price oracle is changed\n     */\n    event NewPriceOracle(PriceOracle oldPriceOracle, PriceOracle newPriceOracle);\n\n    /**\n     * @notice Indicator that this is a Comptroller contract (for inspection)\n     */\n    bool public constant isComptroller = true;\n\n    // closeFactorMantissa must be strictly greater than this value\n    uint constant closeFactorMinMantissa = 5e16; // 0.05\n\n    // closeFactorMantissa must not exceed this value\n    uint constant closeFactorMaxMantissa = 9e17; // 0.9\n\n    // No collateralFactorMantissa may exceed this value\n    uint constant collateralFactorMaxMantissa = 9e17; // 0.9\n\n    // liquidationIncentiveMantissa must be no less than this value\n    uint constant liquidationIncentiveMinMantissa = mantissaOne;\n\n    // liquidationIncentiveMantissa must be no greater than this value\n    uint constant liquidationIncentiveMaxMantissa = 15e17; // 1.5\n\n    constructor() public {\n        admin = msg.sender;\n    }\n\n    /*** Assets You Are In ***/\n\n    /**\n     * @notice Returns the assets an account has entered\n     * @param account The address of the account to pull assets for\n     * @return A dynamic list with the assets the account has entered\n     */\n    function getAssetsIn(address account) external view returns (CToken[] memory) {\n        CToken[] memory assetsIn = accountAssets[account];\n\n        return assetsIn;\n    }\n\n    /**\n     * @notice Returns whether the given account is entered in the given asset\n     * @param account The address of the account to check\n     * @param cToken The cToken to check\n     * @return True if the account is in the asset, otherwise false.\n     */\n    function checkMembership(address account, CToken cToken) external view returns (bool) {\n        return markets[address(cToken)].accountMembership[account];\n    }\n\n    /**\n     * @notice Add assets to be included in account liquidity calculation\n     * @param cTokens The list of addresses of the cToken markets to be enabled\n     * @return Success indicator for whether each corresponding market was entered\n     */\n    function enterMarkets(address[] memory cTokens) public returns (uint[] memory) {\n        uint len = cTokens.length;\n\n        uint[] memory results = new uint[](len);\n        for (uint i = 0; i \u003c len; i++) {\n            CToken cToken = CToken(cTokens[i]);\n            Market storage marketToJoin = markets[address(cToken)];\n\n            if (!marketToJoin.isListed) {\n                // if market is not listed, cannot join move along\n                results[i] = uint(Error.MARKET_NOT_LISTED);\n                continue;\n            }\n\n            if (marketToJoin.accountMembership[msg.sender] == true) {\n                // if already joined, move along\n                results[i] = uint(Error.NO_ERROR);\n                continue;\n            }\n\n            if (accountAssets[msg.sender].length \u003e= maxAssets)  {\n                // if no space, cannot join, move along\n                results[i] = uint(Error.TOO_MANY_ASSETS);\n                continue;\n            }\n\n            // survived the gauntlet, add to list\n            // NOTE: we store these somewhat redundantly as a significant optimization\n            //  this avoids having to iterate through the list for the most common use cases\n            //  that is, only when we need to perform liquidity checks\n            //   and not whenever we want to check if an account is in a particular market\n            marketToJoin.accountMembership[msg.sender] = true;\n            accountAssets[msg.sender].push(cToken);\n\n            emit MarketEntered(cToken, msg.sender);\n\n            results[i] = uint(Error.NO_ERROR);\n        }\n\n        return results;\n    }\n\n    /**\n     * @notice Removes asset from sender\u0027s account liquidity calculation\n     * @dev Sender must not have an outstanding borrow balance in the asset,\n     *  or be providing neccessary collateral for an outstanding borrow.\n     * @param cTokenAddress The address of the asset to be removed\n     * @return Whether or not the account successfully exited the market\n     */\n    function exitMarket(address cTokenAddress) external returns (uint) {\n        CToken cToken = CToken(cTokenAddress);\n        /* Get sender tokensHeld and amountOwed underlying from the cToken */\n        (uint oErr, uint tokensHeld, uint amountOwed, ) = cToken.getAccountSnapshot(msg.sender);\n        require(oErr == 0, \"exitMarket: getAccountSnapshot failed\"); // semi-opaque error code\n\n        /* Fail if the sender has a borrow balance */\n        if (amountOwed != 0) {\n            return fail(Error.NONZERO_BORROW_BALANCE, FailureInfo.EXIT_MARKET_BALANCE_OWED);\n        }\n\n        /* Fail if the sender is not permitted to redeem all of their tokens */\n        uint allowed = redeemAllowedInternal(cTokenAddress, msg.sender, tokensHeld);\n        if (allowed != 0) {\n            return failOpaque(Error.REJECTION, FailureInfo.EXIT_MARKET_REJECTION, allowed);\n        }\n\n        Market storage marketToExit = markets[address(cToken)];\n\n        /* Return true if the sender is not already ‘in’ the market */\n        if (!marketToExit.accountMembership[msg.sender]) {\n            return uint(Error.NO_ERROR);\n        }\n\n        /* Set cToken account membership to false */\n        delete marketToExit.accountMembership[msg.sender];\n\n        /* Delete cToken from the account’s list of assets */\n        // load into memory for faster iteration\n        CToken[] memory userAssetList = accountAssets[msg.sender];\n        uint len = userAssetList.length;\n        uint assetIndex = len;\n        for (uint i = 0; i \u003c len; i++) {\n            if (userAssetList[i] == cToken) {\n                assetIndex = i;\n                break;\n            }\n        }\n\n        // We *must* have found the asset in the list or our redundant data structure is broken\n        assert(assetIndex \u003c len);\n\n        // copy last item in list to location of item to be removed, reduce length by 1\n        CToken[] storage storedList = accountAssets[msg.sender];\n        storedList[assetIndex] = storedList[storedList.length - 1];\n        storedList.length--;\n\n        emit MarketExited(cToken, msg.sender);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /*** Policy Hooks ***/\n\n    /**\n     * @notice Checks if the account should be allowed to mint tokens in the given market\n     * @param cToken The market to verify the mint against\n     * @param minter The account which would get the minted tokens\n     * @param mintAmount The amount of underlying being supplied to the market in exchange for tokens\n     * @return 0 if the mint is allowed, otherwise a semi-opaque error code (See ErrorReporter.sol)\n     */\n    function mintAllowed(address cToken, address minter, uint mintAmount) external returns (uint) {\n        minter;       // currently unused\n        mintAmount;   // currently unused\n\n        if (!markets[cToken].isListed) {\n            return uint(Error.MARKET_NOT_LISTED);\n        }\n\n        // *may include Policy Hook-type checks\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n     * @notice Validates mint and reverts on rejection. May emit logs.\n     * @param cToken Asset being minted\n     * @param minter The address minting the tokens\n     * @param mintAmount The amount of the underlying asset being minted\n     * @param mintTokens The number of tokens being minted\n     */\n    function mintVerify(address cToken, address minter, uint mintAmount, uint mintTokens) external {\n        cToken;       // currently unused\n        minter;       // currently unused\n        mintAmount;   // currently unused\n        mintTokens;   // currently unused\n\n        if (false) {\n            maxAssets = maxAssets; // not pure\n        }\n    }\n\n    /**\n     * @notice Checks if the account should be allowed to redeem tokens in the given market\n     * @param cToken The market to verify the redeem against\n     * @param redeemer The account which would redeem the tokens\n     * @param redeemTokens The number of cTokens to exchange for the underlying asset in the market\n     * @return 0 if the redeem is allowed, otherwise a semi-opaque error code (See ErrorReporter.sol)\n     */\n    function redeemAllowed(address cToken, address redeemer, uint redeemTokens) external returns (uint) {\n        return redeemAllowedInternal(cToken, redeemer, redeemTokens);\n    }\n\n    function redeemAllowedInternal(address cToken, address redeemer, uint redeemTokens) internal view returns (uint) {\n        if (!markets[cToken].isListed) {\n            return uint(Error.MARKET_NOT_LISTED);\n        }\n\n        // *may include Policy Hook-type checks\n\n        /* If the redeemer is not \u0027in\u0027 the market, then we can bypass the liquidity check */\n        if (!markets[cToken].accountMembership[redeemer]) {\n            return uint(Error.NO_ERROR);\n        }\n\n        /* Otherwise, perform a hypothetical liquidity check to guard against shortfall */\n        (Error err, , uint shortfall) = getHypotheticalAccountLiquidityInternal(redeemer, CToken(cToken), redeemTokens, 0);\n        if (err != Error.NO_ERROR) {\n            return uint(err);\n        }\n        if (shortfall \u003e 0) {\n            return uint(Error.INSUFFICIENT_LIQUIDITY);\n        }\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n     * @notice Validates redeem and reverts on rejection. May emit logs.\n     * @param cToken Asset being redeemed\n     * @param redeemer The address redeeming the tokens\n     * @param redeemAmount The amount of the underlying asset being redeemed\n     * @param redeemTokens The number of tokens being redeemed\n     */\n    function redeemVerify(address cToken, address redeemer, uint redeemAmount, uint redeemTokens) external {\n        cToken;         // currently unused\n        redeemer;       // currently unused\n        redeemAmount;   // currently unused\n        redeemTokens;   // currently unused\n\n        // Require tokens is zero or amount is also zero\n        if (redeemTokens == 0 \u0026\u0026 redeemAmount \u003e 0) {\n            revert(\"redeemTokens zero\");\n        }\n    }\n\n    /**\n     * @notice Checks if the account should be allowed to borrow the underlying asset of the given market\n     * @param cToken The market to verify the borrow against\n     * @param borrower The account which would borrow the asset\n     * @param borrowAmount The amount of underlying the account would borrow\n     * @return 0 if the borrow is allowed, otherwise a semi-opaque error code (See ErrorReporter.sol)\n     */\n    function borrowAllowed(address cToken, address borrower, uint borrowAmount) external returns (uint) {\n        if (!markets[cToken].isListed) {\n            return uint(Error.MARKET_NOT_LISTED);\n        }\n\n        // *may include Policy Hook-type checks\n\n        if (!markets[cToken].accountMembership[borrower]) {\n            return uint(Error.MARKET_NOT_ENTERED);\n        }\n\n        if (oracle.getUnderlyingPrice(CToken(cToken)) == 0) {\n            return uint(Error.PRICE_ERROR);\n        }\n\n        (Error err, , uint shortfall) = getHypotheticalAccountLiquidityInternal(borrower, CToken(cToken), 0, borrowAmount);\n        if (err != Error.NO_ERROR) {\n            return uint(err);\n        }\n        if (shortfall \u003e 0) {\n            return uint(Error.INSUFFICIENT_LIQUIDITY);\n        }\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n     * @notice Validates borrow and reverts on rejection. May emit logs.\n     * @param cToken Asset whose underlying is being borrowed\n     * @param borrower The address borrowing the underlying\n     * @param borrowAmount The amount of the underlying asset requested to borrow\n     */\n    function borrowVerify(address cToken, address borrower, uint borrowAmount) external {\n        cToken;         // currently unused\n        borrower;       // currently unused\n        borrowAmount;   // currently unused\n\n        if (false) {\n            maxAssets = maxAssets; // not pure\n        }\n    }\n\n    /**\n     * @notice Checks if the account should be allowed to repay a borrow in the given market\n     * @param cToken The market to verify the repay against\n     * @param payer The account which would repay the asset\n     * @param borrower The account which would borrowed the asset\n     * @param repayAmount The amount of the underlying asset the account would repay\n     * @return 0 if the repay is allowed, otherwise a semi-opaque error code (See ErrorReporter.sol)\n     */\n    function repayBorrowAllowed(\n        address cToken,\n        address payer,\n        address borrower,\n        uint repayAmount) external returns (uint) {\n        payer;         // currently unused\n        borrower;      // currently unused\n        repayAmount;   // currently unused\n\n        if (!markets[cToken].isListed) {\n            return uint(Error.MARKET_NOT_LISTED);\n        }\n\n        // *may include Policy Hook-type checks\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n     * @notice Validates repayBorrow and reverts on rejection. May emit logs.\n     * @param cToken Asset being repaid\n     * @param payer The address repaying the borrow\n     * @param borrower The address of the borrower\n     * @param repayAmount The amount of underlying being repaid\n     */\n    function repayBorrowVerify(\n        address cToken,\n        address payer,\n        address borrower,\n        uint repayAmount,\n        uint borrowerIndex) external {\n        cToken;        // currently unused\n        payer;         // currently unused\n        borrower;      // currently unused\n        repayAmount;   // currently unused\n        borrowerIndex; // currently unused\n\n        if (false) {\n            maxAssets = maxAssets; // not pure\n        }\n    }\n\n    /**\n     * @notice Checks if the liquidation should be allowed to occur\n     * @param cTokenBorrowed Asset which was borrowed by the borrower\n     * @param cTokenCollateral Asset which was used as collateral and will be seized\n     * @param liquidator The address repaying the borrow and seizing the collateral\n     * @param borrower The address of the borrower\n     * @param repayAmount The amount of underlying being repaid\n     */\n    function liquidateBorrowAllowed(\n        address cTokenBorrowed,\n        address cTokenCollateral,\n        address liquidator,\n        address borrower,\n        uint repayAmount) external returns (uint) {\n        liquidator;   // currently unused\n        borrower;     // currently unused\n        repayAmount;  // currently unused\n\n        if (!markets[cTokenBorrowed].isListed || !markets[cTokenCollateral].isListed) {\n            return uint(Error.MARKET_NOT_LISTED);\n        }\n\n        // *may include Policy Hook-type checks\n\n        /* The borrower must have shortfall in order to be liquidatable */\n        (Error err, , uint shortfall) = getAccountLiquidityInternal(borrower);\n        if (err != Error.NO_ERROR) {\n            return uint(err);\n        }\n        if (shortfall == 0) {\n            return uint(Error.INSUFFICIENT_SHORTFALL);\n        }\n\n        /* The liquidator may not repay more than what is allowed by the closeFactor */\n        uint borrowBalance = CToken(cTokenBorrowed).borrowBalanceStored(borrower);\n        (MathError mathErr, uint maxClose) = mulScalarTruncate(Exp({mantissa: closeFactorMantissa}), borrowBalance);\n        if (mathErr != MathError.NO_ERROR) {\n            return uint(Error.MATH_ERROR);\n        }\n        if (repayAmount \u003e maxClose) {\n            return uint(Error.TOO_MUCH_REPAY);\n        }\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n     * @notice Validates liquidateBorrow and reverts on rejection. May emit logs.\n     * @param cTokenBorrowed Asset which was borrowed by the borrower\n     * @param cTokenCollateral Asset which was used as collateral and will be seized\n     * @param liquidator The address repaying the borrow and seizing the collateral\n     * @param borrower The address of the borrower\n     * @param repayAmount The amount of underlying being repaid\n     */\n    function liquidateBorrowVerify(\n        address cTokenBorrowed,\n        address cTokenCollateral,\n        address liquidator,\n        address borrower,\n        uint repayAmount,\n        uint seizeTokens) external {\n        cTokenBorrowed;   // currently unused\n        cTokenCollateral; // currently unused\n        liquidator;       // currently unused\n        borrower;         // currently unused\n        repayAmount;      // currently unused\n        seizeTokens;      // currently unused\n\n        if (false) {\n            maxAssets = maxAssets; // not pure\n        }\n    }\n\n    /**\n     * @notice Checks if the seizing of assets should be allowed to occur\n     * @param cTokenCollateral Asset which was used as collateral and will be seized\n     * @param cTokenBorrowed Asset which was borrowed by the borrower\n     * @param liquidator The address repaying the borrow and seizing the collateral\n     * @param borrower The address of the borrower\n     * @param seizeTokens The number of collateral tokens to seize\n     */\n    function seizeAllowed(\n        address cTokenCollateral,\n        address cTokenBorrowed,\n        address liquidator,\n        address borrower,\n        uint seizeTokens) external returns (uint) {\n        liquidator;       // currently unused\n        borrower;         // currently unused\n        seizeTokens;      // currently unused\n\n        if (!markets[cTokenCollateral].isListed || !markets[cTokenBorrowed].isListed) {\n            return uint(Error.MARKET_NOT_LISTED);\n        }\n\n        if (CToken(cTokenCollateral).comptroller() != CToken(cTokenBorrowed).comptroller()) {\n            return uint(Error.COMPTROLLER_MISMATCH);\n        }\n\n        // *may include Policy Hook-type checks\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n     * @notice Validates seize and reverts on rejection. May emit logs.\n     * @param cTokenCollateral Asset which was used as collateral and will be seized\n     * @param cTokenBorrowed Asset which was borrowed by the borrower\n     * @param liquidator The address repaying the borrow and seizing the collateral\n     * @param borrower The address of the borrower\n     * @param seizeTokens The number of collateral tokens to seize\n     */\n    function seizeVerify(\n        address cTokenCollateral,\n        address cTokenBorrowed,\n        address liquidator,\n        address borrower,\n        uint seizeTokens) external {\n        cTokenCollateral; // currently unused\n        cTokenBorrowed;   // currently unused\n        liquidator;       // currently unused\n        borrower;         // currently unused\n        seizeTokens;      // currently unused\n\n        if (false) {\n            maxAssets = maxAssets; // not pure\n        }\n    }\n\n    /**\n     * @notice Checks if the account should be allowed to transfer tokens in the given market\n     * @param cToken The market to verify the transfer against\n     * @param src The account which sources the tokens\n     * @param dst The account which receives the tokens\n     * @param transferTokens The number of cTokens to transfer\n     * @return 0 if the transfer is allowed, otherwise a semi-opaque error code (See ErrorReporter.sol)\n     */\n    function transferAllowed(address cToken, address src, address dst, uint transferTokens) external returns (uint) {\n        cToken;         // currently unused\n        src;            // currently unused\n        dst;            // currently unused\n        transferTokens; // currently unused\n\n        // *may include Policy Hook-type checks\n\n        // Currently the only consideration is whether or not\n        //  the src is allowed to redeem this many tokens\n        return redeemAllowedInternal(cToken, src, transferTokens);\n    }\n\n    /**\n     * @notice Validates transfer and reverts on rejection. May emit logs.\n     * @param cToken Asset being transferred\n     * @param src The account which sources the tokens\n     * @param dst The account which receives the tokens\n     * @param transferTokens The number of cTokens to transfer\n     */\n    function transferVerify(address cToken, address src, address dst, uint transferTokens) external {\n        cToken;         // currently unused\n        src;            // currently unused\n        dst;            // currently unused\n        transferTokens; // currently unused\n\n        if (false) {\n            maxAssets = maxAssets; // not pure\n        }\n    }\n\n    /*** Liquidity/Liquidation Calculations ***/\n\n    /**\n     * @dev Local vars for avoiding stack-depth limits in calculating account liquidity.\n     *  Note that `cTokenBalance` is the number of cTokens the account owns in the market,\n     *  whereas `borrowBalance` is the amount of underlying that the account has borrowed.\n     */\n    struct AccountLiquidityLocalVars {\n        uint sumCollateral;\n        uint sumBorrowPlusEffects;\n        uint cTokenBalance;\n        uint borrowBalance;\n        uint exchangeRateMantissa;\n        uint oraclePriceMantissa;\n        Exp collateralFactor;\n        Exp exchangeRate;\n        Exp oraclePrice;\n        Exp tokensToEther;\n    }\n\n    /**\n     * @notice Determine the current account liquidity wrt collateral requirements\n     * @return (possible error code (semi-opaque),\n                account liquidity in excess of collateral requirements,\n     *          account shortfall below collateral requirements)\n     */\n    function getAccountLiquidity(address account) public view returns (uint, uint, uint) {\n        (Error err, uint liquidity, uint shortfall) = getHypotheticalAccountLiquidityInternal(account, CToken(0), 0, 0);\n\n        return (uint(err), liquidity, shortfall);\n    }\n\n    /**\n     * @notice Determine the current account liquidity wrt collateral requirements\n     * @return (possible error code,\n                account liquidity in excess of collateral requirements,\n     *          account shortfall below collateral requirements)\n     */\n    function getAccountLiquidityInternal(address account) internal view returns (Error, uint, uint) {\n        return getHypotheticalAccountLiquidityInternal(account, CToken(0), 0, 0);\n    }\n\n    /**\n     * @notice Determine what the account liquidity would be if the given amounts were redeemed/borrowed\n     * @param cTokenModify The market to hypothetically redeem/borrow in\n     * @param account The account to determine liquidity for\n     * @param redeemTokens The number of tokens to hypothetically redeem\n     * @param borrowAmount The amount of underlying to hypothetically borrow\n     * @dev Note that we calculate the exchangeRateStored for each collateral cToken using stored data,\n     *  without calculating accumulated interest.\n     * @return (possible error code,\n                hypothetical account liquidity in excess of collateral requirements,\n     *          hypothetical account shortfall below collateral requirements)\n     */\n    function getHypotheticalAccountLiquidityInternal(\n        address account,\n        CToken cTokenModify,\n        uint redeemTokens,\n        uint borrowAmount) internal view returns (Error, uint, uint) {\n\n        AccountLiquidityLocalVars memory vars; // Holds all our calculation results\n        uint oErr;\n        MathError mErr;\n\n        // For each asset the account is in\n        CToken[] memory assets = accountAssets[account];\n        for (uint i = 0; i \u003c assets.length; i++) {\n            CToken asset = assets[i];\n\n            // Read the balances and exchange rate from the cToken\n            (oErr, vars.cTokenBalance, vars.borrowBalance, vars.exchangeRateMantissa) = asset.getAccountSnapshot(account);\n            if (oErr != 0) { // semi-opaque error code, we assume NO_ERROR == 0 is invariant between upgrades\n                return (Error.SNAPSHOT_ERROR, 0, 0);\n            }\n            vars.collateralFactor = Exp({mantissa: markets[address(asset)].collateralFactorMantissa});\n            vars.exchangeRate = Exp({mantissa: vars.exchangeRateMantissa});\n\n            // Get the normalized price of the asset\n            vars.oraclePriceMantissa = oracle.getUnderlyingPrice(asset);\n            if (vars.oraclePriceMantissa == 0) {\n                return (Error.PRICE_ERROR, 0, 0);\n            }\n            vars.oraclePrice = Exp({mantissa: vars.oraclePriceMantissa});\n\n            // Pre-compute a conversion factor from tokens -\u003e ether (normalized price value)\n            (mErr, vars.tokensToEther) = mulExp3(vars.collateralFactor, vars.exchangeRate, vars.oraclePrice);\n            if (mErr != MathError.NO_ERROR) {\n                return (Error.MATH_ERROR, 0, 0);\n            }\n\n            // sumCollateral += tokensToEther * cTokenBalance\n            (mErr, vars.sumCollateral) = mulScalarTruncateAddUInt(vars.tokensToEther, vars.cTokenBalance, vars.sumCollateral);\n            if (mErr != MathError.NO_ERROR) {\n                return (Error.MATH_ERROR, 0, 0);\n            }\n\n            // sumBorrowPlusEffects += oraclePrice * borrowBalance\n            (mErr, vars.sumBorrowPlusEffects) = mulScalarTruncateAddUInt(vars.oraclePrice, vars.borrowBalance, vars.sumBorrowPlusEffects);\n            if (mErr != MathError.NO_ERROR) {\n                return (Error.MATH_ERROR, 0, 0);\n            }\n\n            // Calculate effects of interacting with cTokenModify\n            if (asset == cTokenModify) {\n                // redeem effect\n                // sumBorrowPlusEffects += tokensToEther * redeemTokens\n                (mErr, vars.sumBorrowPlusEffects) = mulScalarTruncateAddUInt(vars.tokensToEther, redeemTokens, vars.sumBorrowPlusEffects);\n                if (mErr != MathError.NO_ERROR) {\n                    return (Error.MATH_ERROR, 0, 0);\n                }\n\n                // borrow effect\n                // sumBorrowPlusEffects += oraclePrice * borrowAmount\n                (mErr, vars.sumBorrowPlusEffects) = mulScalarTruncateAddUInt(vars.oraclePrice, borrowAmount, vars.sumBorrowPlusEffects);\n                if (mErr != MathError.NO_ERROR) {\n                    return (Error.MATH_ERROR, 0, 0);\n                }\n            }\n        }\n\n        // These are safe, as the underflow condition is checked first\n        if (vars.sumCollateral \u003e vars.sumBorrowPlusEffects) {\n            return (Error.NO_ERROR, vars.sumCollateral - vars.sumBorrowPlusEffects, 0);\n        } else {\n            return (Error.NO_ERROR, 0, vars.sumBorrowPlusEffects - vars.sumCollateral);\n        }\n    }\n\n    /**\n     * @notice Calculate number of tokens of collateral asset to seize given an underlying amount\n     * @dev Used in liquidation (called in cToken.liquidateBorrowFresh)\n     * @param cTokenBorrowed The address of the borrowed cToken\n     * @param cTokenCollateral The address of the collateral cToken\n     * @param repayAmount The amount of cTokenBorrowed underlying to convert into cTokenCollateral tokens\n     * @return (errorCode, number of cTokenCollateral tokens to be seized in a liquidation)\n     */\n    function liquidateCalculateSeizeTokens(address cTokenBorrowed, address cTokenCollateral, uint repayAmount) external view returns (uint, uint) {\n        /* Read oracle prices for borrowed and collateral markets */\n        uint priceBorrowedMantissa = oracle.getUnderlyingPrice(CToken(cTokenBorrowed));\n        uint priceCollateralMantissa = oracle.getUnderlyingPrice(CToken(cTokenCollateral));\n        if (priceBorrowedMantissa == 0 || priceCollateralMantissa == 0) {\n            return (uint(Error.PRICE_ERROR), 0);\n        }\n\n        /*\n         * Get the exchange rate and calculate the number of collateral tokens to seize:\n         *  seizeAmount = repayAmount * liquidationIncentive * priceBorrowed / priceCollateral\n         *  seizeTokens = seizeAmount / exchangeRate\n         *   = repayAmount * (liquidationIncentive * priceBorrowed) / (priceCollateral * exchangeRate)\n         */\n        uint exchangeRateMantissa = CToken(cTokenCollateral).exchangeRateStored(); // Note: reverts on error\n        uint seizeTokens;\n        Exp memory numerator;\n        Exp memory denominator;\n        Exp memory ratio;\n        MathError mathErr;\n\n        (mathErr, numerator) = mulExp(liquidationIncentiveMantissa, priceBorrowedMantissa);\n        if (mathErr != MathError.NO_ERROR) {\n            return (uint(Error.MATH_ERROR), 0);\n        }\n\n        (mathErr, denominator) = mulExp(priceCollateralMantissa, exchangeRateMantissa);\n        if (mathErr != MathError.NO_ERROR) {\n            return (uint(Error.MATH_ERROR), 0);\n        }\n\n        (mathErr, ratio) = divExp(numerator, denominator);\n        if (mathErr != MathError.NO_ERROR) {\n            return (uint(Error.MATH_ERROR), 0);\n        }\n\n        (mathErr, seizeTokens) = mulScalarTruncate(ratio, repayAmount);\n        if (mathErr != MathError.NO_ERROR) {\n            return (uint(Error.MATH_ERROR), 0);\n        }\n\n        return (uint(Error.NO_ERROR), seizeTokens);\n    }\n\n    /*** Admin Functions ***/\n\n    /**\n      * @notice Sets a new price oracle for the comptroller\n      * @dev Admin function to set a new price oracle\n      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n      */\n    function _setPriceOracle(PriceOracle newOracle) public returns (uint) {\n        // Check caller is admin OR currently initialzing as new unitroller implementation\n        if (!adminOrInitializing()) {\n            return fail(Error.UNAUTHORIZED, FailureInfo.SET_PRICE_ORACLE_OWNER_CHECK);\n        }\n\n        // Track the old oracle for the comptroller\n        PriceOracle oldOracle = oracle;\n\n        // Ensure invoke newOracle.isPriceOracle() returns true\n        // require(newOracle.isPriceOracle(), \"oracle method isPriceOracle returned false\");\n\n        // Set comptroller\u0027s oracle to newOracle\n        oracle = newOracle;\n\n        // Emit NewPriceOracle(oldOracle, newOracle)\n        emit NewPriceOracle(oldOracle, newOracle);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n      * @notice Sets the closeFactor used when liquidating borrows\n      * @dev Admin function to set closeFactor\n      * @param newCloseFactorMantissa New close factor, scaled by 1e18\n      * @return uint 0=success, otherwise a failure. (See ErrorReporter for details)\n      */\n    function _setCloseFactor(uint newCloseFactorMantissa) external returns (uint256) {\n        // Check caller is admin OR currently initialzing as new unitroller implementation\n        if (!adminOrInitializing()) {\n            return fail(Error.UNAUTHORIZED, FailureInfo.SET_CLOSE_FACTOR_OWNER_CHECK);\n        }\n\n        Exp memory newCloseFactorExp = Exp({mantissa: newCloseFactorMantissa});\n        Exp memory lowLimit = Exp({mantissa: closeFactorMinMantissa});\n        if (lessThanOrEqualExp(newCloseFactorExp, lowLimit)) {\n            return fail(Error.INVALID_CLOSE_FACTOR, FailureInfo.SET_CLOSE_FACTOR_VALIDATION);\n        }\n\n        Exp memory highLimit = Exp({mantissa: closeFactorMaxMantissa});\n        if (lessThanExp(highLimit, newCloseFactorExp)) {\n            return fail(Error.INVALID_CLOSE_FACTOR, FailureInfo.SET_CLOSE_FACTOR_VALIDATION);\n        }\n\n        uint oldCloseFactorMantissa = closeFactorMantissa;\n        closeFactorMantissa = newCloseFactorMantissa;\n        emit NewCloseFactor(oldCloseFactorMantissa, closeFactorMantissa);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n      * @notice Sets the collateralFactor for a market\n      * @dev Admin function to set per-market collateralFactor\n      * @param cToken The market to set the factor on\n      * @param newCollateralFactorMantissa The new collateral factor, scaled by 1e18\n      * @return uint 0=success, otherwise a failure. (See ErrorReporter for details)\n      */\n    function _setCollateralFactor(CToken cToken, uint newCollateralFactorMantissa) external returns (uint256) {\n        // Check caller is admin\n        if (msg.sender != admin) {\n            return fail(Error.UNAUTHORIZED, FailureInfo.SET_COLLATERAL_FACTOR_OWNER_CHECK);\n        }\n\n        // Verify market is listed\n        Market storage market = markets[address(cToken)];\n        if (!market.isListed) {\n            return fail(Error.MARKET_NOT_LISTED, FailureInfo.SET_COLLATERAL_FACTOR_NO_EXISTS);\n        }\n\n        Exp memory newCollateralFactorExp = Exp({mantissa: newCollateralFactorMantissa});\n\n        // Check collateral factor \u003c= 0.9\n        Exp memory highLimit = Exp({mantissa: collateralFactorMaxMantissa});\n        if (lessThanExp(highLimit, newCollateralFactorExp)) {\n            return fail(Error.INVALID_COLLATERAL_FACTOR, FailureInfo.SET_COLLATERAL_FACTOR_VALIDATION);\n        }\n\n        // If collateral factor != 0, fail if price == 0\n        if (newCollateralFactorMantissa != 0 \u0026\u0026 oracle.getUnderlyingPrice(cToken) == 0) {\n            return fail(Error.PRICE_ERROR, FailureInfo.SET_COLLATERAL_FACTOR_WITHOUT_PRICE);\n        }\n\n        // Set market\u0027s collateral factor to new collateral factor, remember old value\n        uint oldCollateralFactorMantissa = market.collateralFactorMantissa;\n        market.collateralFactorMantissa = newCollateralFactorMantissa;\n\n        // Emit event with asset, old collateral factor, and new collateral factor\n        emit NewCollateralFactor(cToken, oldCollateralFactorMantissa, newCollateralFactorMantissa);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n      * @notice Sets maxAssets which controls how many markets can be entered\n      * @dev Admin function to set maxAssets\n      * @param newMaxAssets New max assets\n      * @return uint 0=success, otherwise a failure. (See ErrorReporter for details)\n      */\n    function _setMaxAssets(uint newMaxAssets) external returns (uint) {\n        // Check caller is admin OR currently initialzing as new unitroller implementation\n        if (!adminOrInitializing()) {\n            return fail(Error.UNAUTHORIZED, FailureInfo.SET_MAX_ASSETS_OWNER_CHECK);\n        }\n\n        uint oldMaxAssets = maxAssets;\n        maxAssets = newMaxAssets;\n        emit NewMaxAssets(oldMaxAssets, newMaxAssets);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n      * @notice Sets liquidationIncentive\n      * @dev Admin function to set liquidationIncentive\n      * @param newLiquidationIncentiveMantissa New liquidationIncentive scaled by 1e18\n      * @return uint 0=success, otherwise a failure. (See ErrorReporter for details)\n      */\n    function _setLiquidationIncentive(uint newLiquidationIncentiveMantissa) external returns (uint) {\n        // Check caller is admin OR currently initialzing as new unitroller implementation\n        if (!adminOrInitializing()) {\n            return fail(Error.UNAUTHORIZED, FailureInfo.SET_LIQUIDATION_INCENTIVE_OWNER_CHECK);\n        }\n\n        // Check de-scaled 1 \u003c= newLiquidationDiscount \u003c= 1.5\n        Exp memory newLiquidationIncentive = Exp({mantissa: newLiquidationIncentiveMantissa});\n        Exp memory minLiquidationIncentive = Exp({mantissa: liquidationIncentiveMinMantissa});\n        if (lessThanExp(newLiquidationIncentive, minLiquidationIncentive)) {\n            return fail(Error.INVALID_LIQUIDATION_INCENTIVE, FailureInfo.SET_LIQUIDATION_INCENTIVE_VALIDATION);\n        }\n\n        Exp memory maxLiquidationIncentive = Exp({mantissa: liquidationIncentiveMaxMantissa});\n        if (lessThanExp(maxLiquidationIncentive, newLiquidationIncentive)) {\n            return fail(Error.INVALID_LIQUIDATION_INCENTIVE, FailureInfo.SET_LIQUIDATION_INCENTIVE_VALIDATION);\n        }\n\n        // Save current value for use in log\n        uint oldLiquidationIncentiveMantissa = liquidationIncentiveMantissa;\n\n        // Set liquidation incentive to new incentive\n        liquidationIncentiveMantissa = newLiquidationIncentiveMantissa;\n\n        // Emit event with old incentive, new incentive\n        emit NewLiquidationIncentive(oldLiquidationIncentiveMantissa, newLiquidationIncentiveMantissa);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n      * @notice Add the market to the markets mapping and set it as listed\n      * @dev Admin function to set isListed and add support for the market\n      * @param cToken The address of the market (token) to list\n      * @return uint 0=success, otherwise a failure. (See enum Error for details)\n      */\n    function _supportMarket(CToken cToken) external returns (uint) {\n        if (msg.sender != admin) {\n            return fail(Error.UNAUTHORIZED, FailureInfo.SUPPORT_MARKET_OWNER_CHECK);\n        }\n\n        if (markets[address(cToken)].isListed) {\n            return fail(Error.MARKET_ALREADY_LISTED, FailureInfo.SUPPORT_MARKET_EXISTS);\n        }\n\n        cToken.isCToken(); // Sanity check to make sure its really a CToken\n\n        markets[address(cToken)] = Market({isListed: true, collateralFactorMantissa: 0});\n        emit MarketListed(cToken);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    function _become(Unitroller unitroller, PriceOracle _oracle, uint _closeFactorMantissa, uint _maxAssets, bool reinitializing) public {\n        require(msg.sender == unitroller.admin(), \"only unitroller admin can change brains\");\n        uint changeStatus = unitroller._acceptImplementation();\n\n        require(changeStatus == 0, \"change not authorized\");\n\n        if (!reinitializing) {\n            Comptroller freshBrainedComptroller = Comptroller(address(unitroller));\n\n            // Ensure invoke _setPriceOracle() = 0\n            uint err = freshBrainedComptroller._setPriceOracle(_oracle);\n            require (err == uint(Error.NO_ERROR), \"set price oracle error\");\n\n            // Ensure invoke _setCloseFactor() = 0\n            err = freshBrainedComptroller._setCloseFactor(_closeFactorMantissa);\n            require (err == uint(Error.NO_ERROR), \"set close factor error\");\n\n            // Ensure invoke _setMaxAssets() = 0\n            err = freshBrainedComptroller._setMaxAssets(_maxAssets);\n            require (err == uint(Error.NO_ERROR), \"set max asssets error\");\n\n            // Ensure invoke _setLiquidationIncentive(liquidationIncentiveMinMantissa) = 0\n            err = freshBrainedComptroller._setLiquidationIncentive(liquidationIncentiveMinMantissa);\n            require (err == uint(Error.NO_ERROR), \"set liquidation incentive error\");\n        }\n    }\n\n    /**\n     * @dev Check that caller is admin or this contract is initializing itself as\n     * the new implementation.\n     * There should be no way to satisfy msg.sender == comptrollerImplementaiton\n     * without tx.origin also being admin, but both are included for extra safety\n     */\n    function adminOrInitializing() internal view returns (bool) {\n        bool initializing = (\n                msg.sender == comptrollerImplementation\n                \u0026\u0026\n                //solium-disable-next-line security/no-tx-origin\n                tx.origin == admin\n        );\n        bool isAdmin = msg.sender == admin;\n        return isAdmin || initializing;\n    }\n}\n"},"ComptrollerInterface.sol":{"content":"pragma solidity ^0.5.8;\n\ninterface ComptrollerInterface {\n    /**\n     * @notice Marker function used for light validation when updating the comptroller of a market\n     * @dev Implementations should simply return true.\n     * @return true\n     */\n    function isComptroller() external view returns (bool);\n\n    /*** Assets You Are In ***/\n\n    function enterMarkets(address[] calldata cTokens) external returns (uint[] memory);\n    function exitMarket(address cToken) external returns (uint);\n\n    /*** Policy Hooks ***/\n\n    function mintAllowed(address cToken, address minter, uint mintAmount) external returns (uint);\n    function mintVerify(address cToken, address minter, uint mintAmount, uint mintTokens) external;\n\n    function redeemAllowed(address cToken, address redeemer, uint redeemTokens) external returns (uint);\n    function redeemVerify(address cToken, address redeemer, uint redeemAmount, uint redeemTokens) external;\n\n    function borrowAllowed(address cToken, address borrower, uint borrowAmount) external returns (uint);\n    function borrowVerify(address cToken, address borrower, uint borrowAmount) external;\n\n    function repayBorrowAllowed(\n        address cToken,\n        address payer,\n        address borrower,\n        uint repayAmount) external returns (uint);\n    function repayBorrowVerify(\n        address cToken,\n        address payer,\n        address borrower,\n        uint repayAmount,\n        uint borrowerIndex) external;\n\n    function liquidateBorrowAllowed(\n        address cTokenBorrowed,\n        address cTokenCollateral,\n        address liquidator,\n        address borrower,\n        uint repayAmount) external returns (uint);\n    function liquidateBorrowVerify(\n        address cTokenBorrowed,\n        address cTokenCollateral,\n        address liquidator,\n        address borrower,\n        uint repayAmount,\n        uint seizeTokens) external;\n\n    function seizeAllowed(\n        address cTokenCollateral,\n        address cTokenBorrowed,\n        address liquidator,\n        address borrower,\n        uint seizeTokens) external returns (uint);\n    function seizeVerify(\n        address cTokenCollateral,\n        address cTokenBorrowed,\n        address liquidator,\n        address borrower,\n        uint seizeTokens) external;\n\n    function transferAllowed(address cToken, address src, address dst, uint transferTokens) external returns (uint);\n    function transferVerify(address cToken, address src, address dst, uint transferTokens) external;\n\n    /*** Liquidity/Liquidation Calculations ***/\n\n    function liquidateCalculateSeizeTokens(\n        address cTokenBorrowed,\n        address cTokenCollateral,\n        uint repayAmount) external view returns (uint, uint);\n}\n"},"ComptrollerStorage.sol":{"content":"pragma solidity ^0.5.8;\n\nimport \"./CToken.sol\";\nimport \"./PriceOracle.sol\";\n\ncontract UnitrollerAdminStorage {\n    /**\n    * @notice Administrator for this contract\n    */\n    address public admin;\n\n    /**\n    * @notice Pending administrator for this contract\n    */\n    address public pendingAdmin;\n\n    /**\n    * @notice Active brains of Unitroller\n    */\n    address public comptrollerImplementation;\n\n    /**\n    * @notice Pending brains of Unitroller\n    */\n    address public pendingComptrollerImplementation;\n}\n\ncontract ComptrollerV1Storage is UnitrollerAdminStorage {\n\n    /**\n     * @notice Oracle which gives the price of any given asset\n     */\n    PriceOracle public oracle;\n\n    /**\n     * @notice Multiplier used to calculate the maximum repayAmount when liquidating a borrow\n     */\n    uint public closeFactorMantissa;\n\n    /**\n     * @notice Multiplier representing the discount on collateral that a liquidator receives\n     */\n    uint public liquidationIncentiveMantissa;\n\n    /**\n     * @notice Max number of assets a single account can participate in (borrow or use as collateral)\n     */\n    uint public maxAssets;\n\n    /**\n     * @notice Per-account mapping of \"assets you are in\", capped by maxAssets\n     */\n    mapping(address =\u003e CToken[]) public accountAssets;\n\n}\n"},"CToken.sol":{"content":"pragma solidity ^0.5.8;\n\nimport \"./ComptrollerInterface.sol\";\nimport \"./ErrorReporter.sol\";\nimport \"./Exponential.sol\";\nimport \"./EIP20Interface.sol\";\nimport \"./EIP20NonStandardInterface.sol\";\nimport \"./ReentrancyGuard.sol\";\nimport \"./InterestRateModel.sol\";\n\n/**\n * @title Compound\u0027s CToken Contract\n * @notice Abstract base for CTokens\n * @author Compound\n */\ncontract CToken is EIP20Interface, Exponential, TokenErrorReporter, ReentrancyGuard {\n    /**\n     * @notice Indicator that this is a CToken contract (for inspection)\n     */\n    bool public constant isCToken = true;\n\n    /**\n     * @notice EIP-20 token name for this token\n     */\n    string public name;\n\n    /**\n     * @notice EIP-20 token symbol for this token\n     */\n    string public symbol;\n\n    /**\n     * @notice EIP-20 token decimals for this token\n     */\n    uint public decimals;\n\n    /**\n     * @notice Maximum borrow rate that can ever be applied (.0005% / block)\n     */\n    uint constant borrowRateMaxMantissa = 5e14;\n\n    /**\n     * @notice Maximum fraction of interest that can be set aside for reserves\n     */\n    uint constant reserveFactorMaxMantissa = 1e18;\n\n    /**\n     * @notice Administrator for this contract\n     */\n    address payable public admin;\n\n    /**\n     * @notice Pending administrator for this contract\n     */\n    address payable public pendingAdmin;\n\n    /**\n     * @notice Contract which oversees inter-cToken operations\n     */\n    ComptrollerInterface public comptroller;\n\n    /**\n     * @notice Model which tells what the current interest rate should be\n     */\n    InterestRateModel public interestRateModel;\n\n    /**\n     * @notice Initial exchange rate used when minting the first CTokens (used when totalSupply = 0)\n     */\n    uint public initialExchangeRateMantissa;\n\n    /**\n     * @notice Fraction of interest currently set aside for reserves\n     */\n    uint public reserveFactorMantissa;\n\n    /**\n     * @notice Block number that interest was last accrued at\n     */\n    uint public accrualBlockNumber;\n\n    /**\n     * @notice Accumulator of total earned interest since the opening of the market\n     */\n    uint public borrowIndex;\n\n    /**\n     * @notice Total amount of outstanding borrows of the underlying in this market\n     */\n    uint public totalBorrows;\n\n    /**\n     * @notice Total amount of reserves of the underlying held in this market\n     */\n    uint public totalReserves;\n\n    /**\n     * @notice Total number of tokens in circulation\n     */\n    uint256 public totalSupply;\n\n    /**\n     * @notice Official record of token balances for each account\n     */\n    mapping (address =\u003e uint256) accountTokens;\n\n    /**\n     * @notice Approved token transfer amounts on behalf of others\n     */\n    mapping (address =\u003e mapping (address =\u003e uint256)) transferAllowances;\n\n    /**\n     * @notice Container for borrow balance information\n     * @member principal Total balance (with accrued interest), after applying the most recent balance-changing action\n     * @member interestIndex Global borrowIndex as of the most recent balance-changing action\n     */\n    struct BorrowSnapshot {\n        uint principal;\n        uint interestIndex;\n    }\n\n    /**\n     * @notice Mapping of account addresses to outstanding borrow balances\n     */\n    mapping(address =\u003e BorrowSnapshot) accountBorrows;\n\n\n    /*** Market Events ***/\n\n    /**\n     * @notice Event emitted when interest is accrued\n     */\n    event AccrueInterest(uint interestAccumulated, uint borrowIndex, uint totalBorrows);\n\n    /**\n     * @notice Event emitted when tokens are minted\n     */\n    event Mint(address minter, uint mintAmount, uint mintTokens);\n\n    /**\n     * @notice Event emitted when tokens are redeemed\n     */\n    event Redeem(address redeemer, uint redeemAmount, uint redeemTokens);\n\n    /**\n     * @notice Event emitted when underlying is borrowed\n     */\n    event Borrow(address borrower, uint borrowAmount, uint accountBorrows, uint totalBorrows);\n\n    /**\n     * @notice Event emitted when a borrow is repaid\n     */\n    event RepayBorrow(address payer, address borrower, uint repayAmount, uint accountBorrows, uint totalBorrows);\n\n    /**\n     * @notice Event emitted when a borrow is liquidated\n     */\n    event LiquidateBorrow(address liquidator, address borrower, uint repayAmount, address cTokenCollateral, uint seizeTokens);\n\n\n    /*** Admin Events ***/\n\n    /**\n     * @notice Event emitted when pendingAdmin is changed\n     */\n    event NewPendingAdmin(address oldPendingAdmin, address newPendingAdmin);\n\n    /**\n     * @notice Event emitted when pendingAdmin is accepted, which means admin is updated\n     */\n    event NewAdmin(address oldAdmin, address newAdmin);\n\n    /**\n     * @notice Event emitted when comptroller is changed\n     */\n    event NewComptroller(ComptrollerInterface oldComptroller, ComptrollerInterface newComptroller);\n\n    /**\n     * @notice Event emitted when interestRateModel is changed\n     */\n    event NewMarketInterestRateModel(InterestRateModel oldInterestRateModel, InterestRateModel newInterestRateModel);\n\n    /**\n     * @notice Event emitted when the reserve factor is changed\n     */\n    event NewReserveFactor(uint oldReserveFactorMantissa, uint newReserveFactorMantissa);\n\n    /**\n     * @notice Event emitted when the reserves are reduced\n     */\n    event ReservesReduced(address admin, uint reduceAmount, uint newTotalReserves);\n\n\n    /**\n     * @notice Construct a new money market\n     * @param comptroller_ The address of the Comptroller\n     * @param interestRateModel_ The address of the interest rate model\n     * @param initialExchangeRateMantissa_ The initial exchange rate, scaled by 1e18\n     * @param name_ EIP-20 name of this token\n     * @param symbol_ EIP-20 symbol of this token\n     * @param decimals_ EIP-20 decimal precision of this token\n     */\n    constructor(ComptrollerInterface comptroller_,\n                InterestRateModel interestRateModel_,\n                uint initialExchangeRateMantissa_,\n                string memory name_,\n                string memory symbol_,\n                uint decimals_) internal {\n        // Set admin to msg.sender\n        admin = msg.sender;\n\n        // Set initial exchange rate\n        initialExchangeRateMantissa = initialExchangeRateMantissa_;\n        require(initialExchangeRateMantissa \u003e 0, \"Initial exchange rate must be greater than zero.\");\n\n        // Set the comptroller\n        uint err = _setComptroller(comptroller_);\n        require(err == uint(Error.NO_ERROR), \"Setting comptroller failed\");\n\n        // Initialize block number and borrow index (block number mocks depend on comptroller being set)\n        accrualBlockNumber = getBlockNumber();\n        borrowIndex = mantissaOne;\n\n        // Set the interest rate model (depends on block number / borrow index)\n        err = _setInterestRateModelFresh(interestRateModel_);\n        require(err == uint(Error.NO_ERROR), \"Setting interest rate model failed\");\n\n        name = name_;\n        symbol = symbol_;\n        decimals = decimals_;\n    }\n\n    /**\n     * @notice Transfer `tokens` tokens from `src` to `dst` by `spender`\n     * @dev Called by both `transfer` and `transferFrom` internally\n     * @param spender The address of the account performing the transfer\n     * @param src The address of the source account\n     * @param dst The address of the destination account\n     * @param tokens The number of tokens to transfer\n     * @return Whether or not the transfer succeeded\n     */\n    function transferTokens(address spender, address src, address dst, uint tokens) internal returns (uint) {\n        /* Fail if transfer not allowed */\n        uint allowed = comptroller.transferAllowed(address(this), src, dst, tokens);\n        if (allowed != 0) {\n            return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.TRANSFER_COMPTROLLER_REJECTION, allowed);\n        }\n\n        /* Do not allow self-transfers */\n        if (src == dst) {\n            return fail(Error.BAD_INPUT, FailureInfo.TRANSFER_NOT_ALLOWED);\n        }\n\n        /* Get the allowance, infinite for the account owner */\n        uint startingAllowance = 0;\n        if (spender == src) {\n            startingAllowance = uint(-1);\n        } else {\n            startingAllowance = transferAllowances[src][spender];\n        }\n\n        /* Do the calculations, checking for {under,over}flow */\n        MathError mathErr;\n        uint allowanceNew;\n        uint srcTokensNew;\n        uint dstTokensNew;\n\n        (mathErr, allowanceNew) = subUInt(startingAllowance, tokens);\n        if (mathErr != MathError.NO_ERROR) {\n            return fail(Error.MATH_ERROR, FailureInfo.TRANSFER_NOT_ALLOWED);\n        }\n\n        (mathErr, srcTokensNew) = subUInt(accountTokens[src], tokens);\n        if (mathErr != MathError.NO_ERROR) {\n            return fail(Error.MATH_ERROR, FailureInfo.TRANSFER_NOT_ENOUGH);\n        }\n\n        (mathErr, dstTokensNew) = addUInt(accountTokens[dst], tokens);\n        if (mathErr != MathError.NO_ERROR) {\n            return fail(Error.MATH_ERROR, FailureInfo.TRANSFER_TOO_MUCH);\n        }\n\n        /////////////////////////\n        // EFFECTS \u0026 INTERACTIONS\n        // (No safe failures beyond this point)\n\n        accountTokens[src] = srcTokensNew;\n        accountTokens[dst] = dstTokensNew;\n\n        /* Eat some of the allowance (if necessary) */\n        if (startingAllowance != uint(-1)) {\n            transferAllowances[src][spender] = allowanceNew;\n        }\n\n        /* We emit a Transfer event */\n        emit Transfer(src, dst, tokens);\n\n        /* We call the defense hook (which checks for under-collateralization) */\n        comptroller.transferVerify(address(this), src, dst, tokens);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n     * @notice Transfer `amount` tokens from `msg.sender` to `dst`\n     * @param dst The address of the destination account\n     * @param amount The number of tokens to transfer\n     * @return Whether or not the transfer succeeded\n     */\n    function transfer(address dst, uint256 amount) external nonReentrant returns (bool) {\n        return transferTokens(msg.sender, msg.sender, dst, amount) == uint(Error.NO_ERROR);\n    }\n\n    /**\n     * @notice Transfer `amount` tokens from `src` to `dst`\n     * @param src The address of the source account\n     * @param dst The address of the destination account\n     * @param amount The number of tokens to transfer\n     * @return Whether or not the transfer succeeded\n     */\n    function transferFrom(address src, address dst, uint256 amount) external nonReentrant returns (bool) {\n        return transferTokens(msg.sender, src, dst, amount) == uint(Error.NO_ERROR);\n    }\n\n    /**\n     * @notice Approve `spender` to transfer up to `amount` from `src`\n     * @dev This will overwrite the approval amount for `spender`\n     *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)\n     * @param spender The address of the account which may transfer tokens\n     * @param amount The number of tokens that are approved (-1 means infinite)\n     * @return Whether or not the approval succeeded\n     */\n    function approve(address spender, uint256 amount) external returns (bool) {\n        address src = msg.sender;\n        transferAllowances[src][spender] = amount;\n        emit Approval(src, spender, amount);\n        return true;\n    }\n\n    /**\n     * @notice Get the current allowance from `owner` for `spender`\n     * @param owner The address of the account which owns the tokens to be spent\n     * @param spender The address of the account which may transfer tokens\n     * @return The number of tokens allowed to be spent (-1 means infinite)\n     */\n    function allowance(address owner, address spender) external view returns (uint256) {\n        return transferAllowances[owner][spender];\n    }\n\n    /**\n     * @notice Get the token balance of the `owner`\n     * @param owner The address of the account to query\n     * @return The number of tokens owned by `owner`\n     */\n    function balanceOf(address owner) external view returns (uint256) {\n        return accountTokens[owner];\n    }\n\n    /**\n     * @notice Get the underlying balance of the `owner`\n     * @dev This also accrues interest in a transaction\n     * @param owner The address of the account to query\n     * @return The amount of underlying owned by `owner`\n     */\n    function balanceOfUnderlying(address owner) external returns (uint) {\n        Exp memory exchangeRate = Exp({mantissa: exchangeRateCurrent()});\n        (MathError mErr, uint balance) = mulScalarTruncate(exchangeRate, accountTokens[owner]);\n        require(mErr == MathError.NO_ERROR);\n        return balance;\n    }\n\n    /**\n     * @notice Get a snapshot of the account\u0027s balances, and the cached exchange rate\n     * @dev This is used by comptroller to more efficiently perform liquidity checks.\n     * @param account Address of the account to snapshot\n     * @return (possible error, token balance, borrow balance, exchange rate mantissa)\n     */\n    function getAccountSnapshot(address account) external view returns (uint, uint, uint, uint) {\n        uint cTokenBalance = accountTokens[account];\n        uint borrowBalance;\n        uint exchangeRateMantissa;\n\n        MathError mErr;\n\n        (mErr, borrowBalance) = borrowBalanceStoredInternal(account);\n        if (mErr != MathError.NO_ERROR) {\n            return (uint(Error.MATH_ERROR), 0, 0, 0);\n        }\n\n        (mErr, exchangeRateMantissa) = exchangeRateStoredInternal();\n        if (mErr != MathError.NO_ERROR) {\n            return (uint(Error.MATH_ERROR), 0, 0, 0);\n        }\n\n        return (uint(Error.NO_ERROR), cTokenBalance, borrowBalance, exchangeRateMantissa);\n    }\n\n    /**\n     * @dev Function to simply retrieve block number\n     *  This exists mainly for inheriting test contracts to stub this result.\n     */\n    function getBlockNumber() internal view returns (uint) {\n        return block.number;\n    }\n\n    /**\n     * @notice Returns the current per-block borrow interest rate for this cToken\n     * @return The borrow interest rate per block, scaled by 1e18\n     */\n    function borrowRatePerBlock() external view returns (uint) {\n        (uint opaqueErr, uint borrowRateMantissa) = interestRateModel.getBorrowRate(getCashPrior(), totalBorrows, totalReserves);\n        require(opaqueErr == 0, \"borrowRatePerBlock: interestRateModel.borrowRate failed\"); // semi-opaque\n        return borrowRateMantissa;\n    }\n\n    /**\n     * @notice Returns the current per-block supply interest rate for this cToken\n     * @return The supply interest rate per block, scaled by 1e18\n     */\n    function supplyRatePerBlock() external view returns (uint) {\n        /* We calculate the supply rate:\n         *  underlying = totalSupply × exchangeRate\n         *  borrowsPer = totalBorrows ÷ underlying\n         *  supplyRate = borrowRate × (1-reserveFactor) × borrowsPer\n         */\n        uint exchangeRateMantissa = exchangeRateStored();\n\n        (uint e0, uint borrowRateMantissa) = interestRateModel.getBorrowRate(getCashPrior(), totalBorrows, totalReserves);\n        require(e0 == 0, \"supplyRatePerBlock: calculating borrowRate failed\"); // semi-opaque\n\n        (MathError e1, Exp memory underlying) = mulScalar(Exp({mantissa: exchangeRateMantissa}), totalSupply);\n        require(e1 == MathError.NO_ERROR, \"supplyRatePerBlock: calculating underlying failed\");\n\n        (MathError e2, Exp memory borrowsPer) = divScalarByExp(totalBorrows, underlying);\n        require(e2 == MathError.NO_ERROR, \"supplyRatePerBlock: calculating borrowsPer failed\");\n\n        (MathError e3, Exp memory oneMinusReserveFactor) = subExp(Exp({mantissa: mantissaOne}), Exp({mantissa: reserveFactorMantissa}));\n        require(e3 == MathError.NO_ERROR, \"supplyRatePerBlock: calculating oneMinusReserveFactor failed\");\n\n        (MathError e4, Exp memory supplyRate) = mulExp3(Exp({mantissa: borrowRateMantissa}), oneMinusReserveFactor, borrowsPer);\n        require(e4 == MathError.NO_ERROR, \"supplyRatePerBlock: calculating supplyRate failed\");\n\n        return supplyRate.mantissa;\n    }\n\n    /**\n     * @notice Returns the current total borrows plus accrued interest\n     * @return The total borrows with interest\n     */\n    function totalBorrowsCurrent() external nonReentrant returns (uint) {\n        require(accrueInterest() == uint(Error.NO_ERROR), \"accrue interest failed\");\n        return totalBorrows;\n    }\n\n    /**\n     * @notice Accrue interest to updated borrowIndex and then calculate account\u0027s borrow balance using the updated borrowIndex\n     * @param account The address whose balance should be calculated after updating borrowIndex\n     * @return The calculated balance\n     */\n    function borrowBalanceCurrent(address account) external nonReentrant returns (uint) {\n        require(accrueInterest() == uint(Error.NO_ERROR), \"accrue interest failed\");\n        return borrowBalanceStored(account);\n    }\n\n    /**\n     * @notice Return the borrow balance of account based on stored data\n     * @param account The address whose balance should be calculated\n     * @return The calculated balance\n     */\n    function borrowBalanceStored(address account) public view returns (uint) {\n        (MathError err, uint result) = borrowBalanceStoredInternal(account);\n        require(err == MathError.NO_ERROR, \"borrowBalanceStored: borrowBalanceStoredInternal failed\");\n        return result;\n    }\n\n    /**\n     * @notice Return the borrow balance of account based on stored data\n     * @param account The address whose balance should be calculated\n     * @return (error code, the calculated balance or 0 if error code is non-zero)\n     */\n    function borrowBalanceStoredInternal(address account) internal view returns (MathError, uint) {\n        /* Note: we do not assert that the market is up to date */\n        MathError mathErr;\n        uint principalTimesIndex;\n        uint result;\n\n        /* Get borrowBalance and borrowIndex */\n        BorrowSnapshot storage borrowSnapshot = accountBorrows[account];\n\n        /* If borrowBalance = 0 then borrowIndex is likely also 0.\n         * Rather than failing the calculation with a division by 0, we immediately return 0 in this case.\n         */\n        if (borrowSnapshot.principal == 0) {\n            return (MathError.NO_ERROR, 0);\n        }\n\n        /* Calculate new borrow balance using the interest index:\n         *  recentBorrowBalance = borrower.borrowBalance * market.borrowIndex / borrower.borrowIndex\n         */\n        (mathErr, principalTimesIndex) = mulUInt(borrowSnapshot.principal, borrowIndex);\n        if (mathErr != MathError.NO_ERROR) {\n            return (mathErr, 0);\n        }\n\n        (mathErr, result) = divUInt(principalTimesIndex, borrowSnapshot.interestIndex);\n        if (mathErr != MathError.NO_ERROR) {\n            return (mathErr, 0);\n        }\n\n        return (MathError.NO_ERROR, result);\n    }\n\n    /**\n     * @notice Accrue interest then return the up-to-date exchange rate\n     * @return Calculated exchange rate scaled by 1e18\n     */\n    function exchangeRateCurrent() public nonReentrant returns (uint) {\n        require(accrueInterest() == uint(Error.NO_ERROR), \"accrue interest failed\");\n        return exchangeRateStored();\n    }\n\n    /**\n     * @notice Calculates the exchange rate from the underlying to the CToken\n     * @dev This function does not accrue interest before calculating the exchange rate\n     * @return Calculated exchange rate scaled by 1e18\n     */\n    function exchangeRateStored() public view returns (uint) {\n        (MathError err, uint result) = exchangeRateStoredInternal();\n        require(err == MathError.NO_ERROR, \"exchangeRateStored: exchangeRateStoredInternal failed\");\n        return result;\n    }\n\n    /**\n     * @notice Calculates the exchange rate from the underlying to the CToken\n     * @dev This function does not accrue interest before calculating the exchange rate\n     * @return (error code, calculated exchange rate scaled by 1e18)\n     */\n    function exchangeRateStoredInternal() internal view returns (MathError, uint) {\n        if (totalSupply == 0) {\n            /*\n             * If there are no tokens minted:\n             *  exchangeRate = initialExchangeRate\n             */\n            return (MathError.NO_ERROR, initialExchangeRateMantissa);\n        } else {\n            /*\n             * Otherwise:\n             *  exchangeRate = (totalCash + totalBorrows - totalReserves) / totalSupply\n             */\n            uint totalCash = getCashPrior();\n            uint cashPlusBorrowsMinusReserves;\n            Exp memory exchangeRate;\n            MathError mathErr;\n\n            (mathErr, cashPlusBorrowsMinusReserves) = addThenSubUInt(totalCash, totalBorrows, totalReserves);\n            if (mathErr != MathError.NO_ERROR) {\n                return (mathErr, 0);\n            }\n\n            (mathErr, exchangeRate) = getExp(cashPlusBorrowsMinusReserves, totalSupply);\n            if (mathErr != MathError.NO_ERROR) {\n                return (mathErr, 0);\n            }\n\n            return (MathError.NO_ERROR, exchangeRate.mantissa);\n        }\n    }\n\n    /**\n     * @notice Get cash balance of this cToken in the underlying asset\n     * @return The quantity of underlying asset owned by this contract\n     */\n    function getCash() external view returns (uint) {\n        return getCashPrior();\n    }\n\n    struct AccrueInterestLocalVars {\n        MathError mathErr;\n        uint opaqueErr;\n        uint borrowRateMantissa;\n        uint currentBlockNumber;\n        uint blockDelta;\n\n        Exp simpleInterestFactor;\n\n        uint interestAccumulated;\n        uint totalBorrowsNew;\n        uint totalReservesNew;\n        uint borrowIndexNew;\n    }\n\n    /**\n      * @notice Applies accrued interest to total borrows and reserves.\n      * @dev This calculates interest accrued from the last checkpointed block\n      *      up to the current block and writes new checkpoint to storage.\n      */\n    function accrueInterest() public returns (uint) {\n        AccrueInterestLocalVars memory vars;\n\n        /* Calculate the current borrow interest rate */\n        (vars.opaqueErr, vars.borrowRateMantissa) = interestRateModel.getBorrowRate(getCashPrior(), totalBorrows, totalReserves);\n        require(vars.borrowRateMantissa \u003c= borrowRateMaxMantissa, \"borrow rate is absurdly high\");\n        if (vars.opaqueErr != 0) {\n            return failOpaque(Error.INTEREST_RATE_MODEL_ERROR, FailureInfo.ACCRUE_INTEREST_BORROW_RATE_CALCULATION_FAILED, vars.opaqueErr);\n        }\n\n        /* Remember the initial block number */\n        vars.currentBlockNumber = getBlockNumber();\n\n        /* Calculate the number of blocks elapsed since the last accrual */\n        (vars.mathErr, vars.blockDelta) = subUInt(vars.currentBlockNumber, accrualBlockNumber);\n        assert(vars.mathErr == MathError.NO_ERROR); // Block delta should always succeed and if it doesn\u0027t, blow up.\n\n        /*\n         * Calculate the interest accumulated into borrows and reserves and the new index:\n         *  simpleInterestFactor = borrowRate * blockDelta\n         *  interestAccumulated = simpleInterestFactor * totalBorrows\n         *  totalBorrowsNew = interestAccumulated + totalBorrows\n         *  totalReservesNew = interestAccumulated * reserveFactor + totalReserves\n         *  borrowIndexNew = simpleInterestFactor * borrowIndex + borrowIndex\n         */\n        (vars.mathErr, vars.simpleInterestFactor) = mulScalar(Exp({mantissa: vars.borrowRateMantissa}), vars.blockDelta);\n        if (vars.mathErr != MathError.NO_ERROR) {\n            return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_SIMPLE_INTEREST_FACTOR_CALCULATION_FAILED, uint(vars.mathErr));\n        }\n\n        (vars.mathErr, vars.interestAccumulated) = mulScalarTruncate(vars.simpleInterestFactor, totalBorrows);\n        if (vars.mathErr != MathError.NO_ERROR) {\n            return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_ACCUMULATED_INTEREST_CALCULATION_FAILED, uint(vars.mathErr));\n        }\n\n        (vars.mathErr, vars.totalBorrowsNew) = addUInt(vars.interestAccumulated, totalBorrows);\n        if (vars.mathErr != MathError.NO_ERROR) {\n            return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_NEW_TOTAL_BORROWS_CALCULATION_FAILED, uint(vars.mathErr));\n        }\n\n        (vars.mathErr, vars.totalReservesNew) = mulScalarTruncateAddUInt(Exp({mantissa: reserveFactorMantissa}), vars.interestAccumulated, totalReserves);\n        if (vars.mathErr != MathError.NO_ERROR) {\n            return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_NEW_TOTAL_RESERVES_CALCULATION_FAILED, uint(vars.mathErr));\n        }\n\n        (vars.mathErr, vars.borrowIndexNew) = mulScalarTruncateAddUInt(vars.simpleInterestFactor, borrowIndex, borrowIndex);\n        if (vars.mathErr != MathError.NO_ERROR) {\n            return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_NEW_BORROW_INDEX_CALCULATION_FAILED, uint(vars.mathErr));\n        }\n\n        /////////////////////////\n        // EFFECTS \u0026 INTERACTIONS\n        // (No safe failures beyond this point)\n\n        /* We write the previously calculated values into storage */\n        accrualBlockNumber = vars.currentBlockNumber;\n        borrowIndex = vars.borrowIndexNew;\n        totalBorrows = vars.totalBorrowsNew;\n        totalReserves = vars.totalReservesNew;\n\n        /* We emit an AccrueInterest event */\n        emit AccrueInterest(vars.interestAccumulated, vars.borrowIndexNew, totalBorrows);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n     * @notice Sender supplies assets into the market and receives cTokens in exchange\n     * @dev Accrues interest whether or not the operation succeeds, unless reverted\n     * @param mintAmount The amount of the underlying asset to supply\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function mintInternal(uint mintAmount) internal nonReentrant returns (uint) {\n        uint error = accrueInterest();\n        if (error != uint(Error.NO_ERROR)) {\n            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed\n            return fail(Error(error), FailureInfo.MINT_ACCRUE_INTEREST_FAILED);\n        }\n        // mintFresh emits the actual Mint event if successful and logs on errors, so we don\u0027t need to\n        return mintFresh(msg.sender, mintAmount);\n    }\n\n    struct MintLocalVars {\n        Error err;\n        MathError mathErr;\n        uint exchangeRateMantissa;\n        uint mintTokens;\n        uint totalSupplyNew;\n        uint accountTokensNew;\n    }\n\n    /**\n     * @notice User supplies assets into the market and receives cTokens in exchange\n     * @dev Assumes interest has already been accrued up to the current block\n     * @param minter The address of the account which is supplying the assets\n     * @param mintAmount The amount of the underlying asset to supply\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function mintFresh(address minter, uint mintAmount) internal returns (uint) {\n        /* Fail if mint not allowed */\n        uint allowed = comptroller.mintAllowed(address(this), minter, mintAmount);\n        if (allowed != 0) {\n            return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.MINT_COMPTROLLER_REJECTION, allowed);\n        }\n\n        /* Verify market\u0027s block number equals current block number */\n        if (accrualBlockNumber != getBlockNumber()) {\n            return fail(Error.MARKET_NOT_FRESH, FailureInfo.MINT_FRESHNESS_CHECK);\n        }\n\n        MintLocalVars memory vars;\n\n        /* Fail if checkTransferIn fails */\n        vars.err = checkTransferIn(minter, mintAmount);\n        if (vars.err != Error.NO_ERROR) {\n            return fail(vars.err, FailureInfo.MINT_TRANSFER_IN_NOT_POSSIBLE);\n        }\n\n        /*\n         * We get the current exchange rate and calculate the number of cTokens to be minted:\n         *  mintTokens = mintAmount / exchangeRate\n         */\n        (vars.mathErr, vars.exchangeRateMantissa) = exchangeRateStoredInternal();\n        if (vars.mathErr != MathError.NO_ERROR) {\n            return failOpaque(Error.MATH_ERROR, FailureInfo.MINT_EXCHANGE_RATE_READ_FAILED, uint(vars.mathErr));\n        }\n\n        (vars.mathErr, vars.mintTokens) = divScalarByExpTruncate(mintAmount, Exp({mantissa: vars.exchangeRateMantissa}));\n        if (vars.mathErr != MathError.NO_ERROR) {\n            return failOpaque(Error.MATH_ERROR, FailureInfo.MINT_EXCHANGE_CALCULATION_FAILED, uint(vars.mathErr));\n        }\n\n        /*\n         * We calculate the new total supply of cTokens and minter token balance, checking for overflow:\n         *  totalSupplyNew = totalSupply + mintTokens\n         *  accountTokensNew = accountTokens[minter] + mintTokens\n         */\n        (vars.mathErr, vars.totalSupplyNew) = addUInt(totalSupply, vars.mintTokens);\n        if (vars.mathErr != MathError.NO_ERROR) {\n            return failOpaque(Error.MATH_ERROR, FailureInfo.MINT_NEW_TOTAL_SUPPLY_CALCULATION_FAILED, uint(vars.mathErr));\n        }\n\n        (vars.mathErr, vars.accountTokensNew) = addUInt(accountTokens[minter], vars.mintTokens);\n        if (vars.mathErr != MathError.NO_ERROR) {\n            return failOpaque(Error.MATH_ERROR, FailureInfo.MINT_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));\n        }\n\n        /////////////////////////\n        // EFFECTS \u0026 INTERACTIONS\n        // (No safe failures beyond this point)\n\n        /*\n         * We call doTransferIn for the minter and the mintAmount\n         *  Note: The cToken must handle variations between ERC-20 and ETH underlying.\n         *  On success, the cToken holds an additional mintAmount of cash.\n         *  If doTransferIn fails despite the fact we checked pre-conditions,\n         *   we revert because we can\u0027t be sure if side effects occurred.\n         */\n        vars.err = doTransferIn(minter, mintAmount);\n        if (vars.err != Error.NO_ERROR) {\n            return fail(vars.err, FailureInfo.MINT_TRANSFER_IN_FAILED);\n        }\n\n        /* We write previously calculated values into storage */\n        totalSupply = vars.totalSupplyNew;\n        accountTokens[minter] = vars.accountTokensNew;\n\n        /* We emit a Mint event, and a Transfer event */\n        emit Mint(minter, mintAmount, vars.mintTokens);\n        emit Transfer(address(this), minter, vars.mintTokens);\n\n        /* We call the defense hook */\n        comptroller.mintVerify(address(this), minter, mintAmount, vars.mintTokens);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n     * @notice Sender redeems cTokens in exchange for the underlying asset\n     * @dev Accrues interest whether or not the operation succeeds, unless reverted\n     * @param redeemTokens The number of cTokens to redeem into underlying\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function redeemInternal(uint redeemTokens) internal nonReentrant returns (uint) {\n        uint error = accrueInterest();\n        if (error != uint(Error.NO_ERROR)) {\n            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted redeem failed\n            return fail(Error(error), FailureInfo.REDEEM_ACCRUE_INTEREST_FAILED);\n        }\n        // redeemFresh emits redeem-specific logs on errors, so we don\u0027t need to\n        return redeemFresh(msg.sender, redeemTokens, 0);\n    }\n\n    /**\n     * @notice Sender redeems cTokens in exchange for a specified amount of underlying asset\n     * @dev Accrues interest whether or not the operation succeeds, unless reverted\n     * @param redeemAmount The amount of underlying to redeem\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function redeemUnderlyingInternal(uint redeemAmount) internal nonReentrant returns (uint) {\n        uint error = accrueInterest();\n        if (error != uint(Error.NO_ERROR)) {\n            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted redeem failed\n            return fail(Error(error), FailureInfo.REDEEM_ACCRUE_INTEREST_FAILED);\n        }\n        // redeemFresh emits redeem-specific logs on errors, so we don\u0027t need to\n        return redeemFresh(msg.sender, 0, redeemAmount);\n    }\n\n    struct RedeemLocalVars {\n        Error err;\n        MathError mathErr;\n        uint exchangeRateMantissa;\n        uint redeemTokens;\n        uint redeemAmount;\n        uint totalSupplyNew;\n        uint accountTokensNew;\n    }\n\n    /**\n     * @notice User redeems cTokens in exchange for the underlying asset\n     * @dev Assumes interest has already been accrued up to the current block\n     * @param redeemer The address of the account which is redeeming the tokens\n     * @param redeemTokensIn The number of cTokens to redeem into underlying (only one of redeemTokensIn or redeemAmountIn may be zero)\n     * @param redeemAmountIn The number of cTokens to redeem into underlying (only one of redeemTokensIn or redeemAmountIn may be zero)\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function redeemFresh(address payable redeemer, uint redeemTokensIn, uint redeemAmountIn) internal returns (uint) {\n        require(redeemTokensIn == 0 || redeemAmountIn == 0, \"one of redeemTokensIn or redeemAmountIn must be zero\");\n\n        RedeemLocalVars memory vars;\n\n        /* exchangeRate = invoke Exchange Rate Stored() */\n        (vars.mathErr, vars.exchangeRateMantissa) = exchangeRateStoredInternal();\n        if (vars.mathErr != MathError.NO_ERROR) {\n            return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_EXCHANGE_RATE_READ_FAILED, uint(vars.mathErr));\n        }\n\n        /* If redeemTokensIn \u003e 0: */\n        if (redeemTokensIn \u003e 0) {\n            /*\n             * We calculate the exchange rate and the amount of underlying to be redeemed:\n             *  redeemTokens = redeemTokensIn\n             *  redeemAmount = redeemTokensIn x exchangeRateCurrent\n             */\n            vars.redeemTokens = redeemTokensIn;\n\n            (vars.mathErr, vars.redeemAmount) = mulScalarTruncate(Exp({mantissa: vars.exchangeRateMantissa}), redeemTokensIn);\n            if (vars.mathErr != MathError.NO_ERROR) {\n                return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_EXCHANGE_TOKENS_CALCULATION_FAILED, uint(vars.mathErr));\n            }\n        } else {\n            /*\n             * We get the current exchange rate and calculate the amount to be redeemed:\n             *  redeemTokens = redeemAmountIn / exchangeRate\n             *  redeemAmount = redeemAmountIn\n             */\n\n            (vars.mathErr, vars.redeemTokens) = divScalarByExpTruncate(redeemAmountIn, Exp({mantissa: vars.exchangeRateMantissa}));\n            if (vars.mathErr != MathError.NO_ERROR) {\n                return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_EXCHANGE_AMOUNT_CALCULATION_FAILED, uint(vars.mathErr));\n            }\n\n            vars.redeemAmount = redeemAmountIn;\n        }\n\n        /* Fail if redeem not allowed */\n        uint allowed = comptroller.redeemAllowed(address(this), redeemer, vars.redeemTokens);\n        if (allowed != 0) {\n            return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.REDEEM_COMPTROLLER_REJECTION, allowed);\n        }\n\n        /* Verify market\u0027s block number equals current block number */\n        if (accrualBlockNumber != getBlockNumber()) {\n            return fail(Error.MARKET_NOT_FRESH, FailureInfo.REDEEM_FRESHNESS_CHECK);\n        }\n\n        /*\n         * We calculate the new total supply and redeemer balance, checking for underflow:\n         *  totalSupplyNew = totalSupply - redeemTokens\n         *  accountTokensNew = accountTokens[redeemer] - redeemTokens\n         */\n        (vars.mathErr, vars.totalSupplyNew) = subUInt(totalSupply, vars.redeemTokens);\n        if (vars.mathErr != MathError.NO_ERROR) {\n            return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_NEW_TOTAL_SUPPLY_CALCULATION_FAILED, uint(vars.mathErr));\n        }\n\n        (vars.mathErr, vars.accountTokensNew) = subUInt(accountTokens[redeemer], vars.redeemTokens);\n        if (vars.mathErr != MathError.NO_ERROR) {\n            return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));\n        }\n\n        /* Fail gracefully if protocol has insufficient cash */\n        if (getCashPrior() \u003c vars.redeemAmount) {\n            return fail(Error.TOKEN_INSUFFICIENT_CASH, FailureInfo.REDEEM_TRANSFER_OUT_NOT_POSSIBLE);\n        }\n\n        /////////////////////////\n        // EFFECTS \u0026 INTERACTIONS\n        // (No safe failures beyond this point)\n\n        /*\n         * We invoke doTransferOut for the redeemer and the redeemAmount.\n         *  Note: The cToken must handle variations between ERC-20 and ETH underlying.\n         *  On success, the cToken has redeemAmount less of cash.\n         *  If doTransferOut fails despite the fact we checked pre-conditions,\n         *   we revert because we can\u0027t be sure if side effects occurred.\n         */\n        vars.err = doTransferOut(redeemer, vars.redeemAmount);\n        require(vars.err == Error.NO_ERROR, \"redeem transfer out failed\");\n\n        /* We write previously calculated values into storage */\n        totalSupply = vars.totalSupplyNew;\n        accountTokens[redeemer] = vars.accountTokensNew;\n\n        /* We emit a Transfer event, and a Redeem event */\n        emit Transfer(redeemer, address(this), vars.redeemTokens);\n        emit Redeem(redeemer, vars.redeemAmount, vars.redeemTokens);\n\n        /* We call the defense hook */\n        comptroller.redeemVerify(address(this), redeemer, vars.redeemAmount, vars.redeemTokens);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n      * @notice Sender borrows assets from the protocol to their own address\n      * @param borrowAmount The amount of the underlying asset to borrow\n      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n      */\n    function borrowInternal(uint borrowAmount) internal nonReentrant returns (uint) {\n        uint error = accrueInterest();\n        if (error != uint(Error.NO_ERROR)) {\n            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed\n            return fail(Error(error), FailureInfo.BORROW_ACCRUE_INTEREST_FAILED);\n        }\n        // borrowFresh emits borrow-specific logs on errors, so we don\u0027t need to\n        return borrowFresh(msg.sender, borrowAmount);\n    }\n\n    struct BorrowLocalVars {\n        Error err;\n        MathError mathErr;\n        uint accountBorrows;\n        uint accountBorrowsNew;\n        uint totalBorrowsNew;\n    }\n\n    /**\n      * @notice Users borrow assets from the protocol to their own address\n      * @param borrowAmount The amount of the underlying asset to borrow\n      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n      */\n    function borrowFresh(address payable borrower, uint borrowAmount) internal returns (uint) {\n        /* Fail if borrow not allowed */\n        uint allowed = comptroller.borrowAllowed(address(this), borrower, borrowAmount);\n        if (allowed != 0) {\n            return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.BORROW_COMPTROLLER_REJECTION, allowed);\n        }\n\n        /* Verify market\u0027s block number equals current block number */\n        if (accrualBlockNumber != getBlockNumber()) {\n            return fail(Error.MARKET_NOT_FRESH, FailureInfo.BORROW_FRESHNESS_CHECK);\n        }\n\n        /* Fail gracefully if protocol has insufficient underlying cash */\n        if (getCashPrior() \u003c borrowAmount) {\n            return fail(Error.TOKEN_INSUFFICIENT_CASH, FailureInfo.BORROW_CASH_NOT_AVAILABLE);\n        }\n\n        BorrowLocalVars memory vars;\n\n        /*\n         * We calculate the new borrower and total borrow balances, failing on overflow:\n         *  accountBorrowsNew = accountBorrows + borrowAmount\n         *  totalBorrowsNew = totalBorrows + borrowAmount\n         */\n        (vars.mathErr, vars.accountBorrows) = borrowBalanceStoredInternal(borrower);\n        if (vars.mathErr != MathError.NO_ERROR) {\n            return failOpaque(Error.MATH_ERROR, FailureInfo.BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));\n        }\n\n        (vars.mathErr, vars.accountBorrowsNew) = addUInt(vars.accountBorrows, borrowAmount);\n        if (vars.mathErr != MathError.NO_ERROR) {\n            return failOpaque(Error.MATH_ERROR, FailureInfo.BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));\n        }\n\n        (vars.mathErr, vars.totalBorrowsNew) = addUInt(totalBorrows, borrowAmount);\n        if (vars.mathErr != MathError.NO_ERROR) {\n            return failOpaque(Error.MATH_ERROR, FailureInfo.BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));\n        }\n\n        /////////////////////////\n        // EFFECTS \u0026 INTERACTIONS\n        // (No safe failures beyond this point)\n\n        /*\n         * We invoke doTransferOut for the borrower and the borrowAmount.\n         *  Note: The cToken must handle variations between ERC-20 and ETH underlying.\n         *  On success, the cToken borrowAmount less of cash.\n         *  If doTransferOut fails despite the fact we checked pre-conditions,\n         *   we revert because we can\u0027t be sure if side effects occurred.\n         */\n        vars.err = doTransferOut(borrower, borrowAmount);\n        require(vars.err == Error.NO_ERROR, \"borrow transfer out failed\");\n\n        /* We write the previously calculated values into storage */\n        accountBorrows[borrower].principal = vars.accountBorrowsNew;\n        accountBorrows[borrower].interestIndex = borrowIndex;\n        totalBorrows = vars.totalBorrowsNew;\n\n        /* We emit a Borrow event */\n        emit Borrow(borrower, borrowAmount, vars.accountBorrowsNew, vars.totalBorrowsNew);\n\n        /* We call the defense hook */\n        comptroller.borrowVerify(address(this), borrower, borrowAmount);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n     * @notice Sender repays their own borrow\n     * @param repayAmount The amount to repay\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function repayBorrowInternal(uint repayAmount) internal nonReentrant returns (uint) {\n        uint error = accrueInterest();\n        if (error != uint(Error.NO_ERROR)) {\n            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed\n            return fail(Error(error), FailureInfo.REPAY_BORROW_ACCRUE_INTEREST_FAILED);\n        }\n        // repayBorrowFresh emits repay-borrow-specific logs on errors, so we don\u0027t need to\n        return repayBorrowFresh(msg.sender, msg.sender, repayAmount);\n    }\n\n    /**\n     * @notice Sender repays a borrow belonging to borrower\n     * @param borrower the account with the debt being payed off\n     * @param repayAmount The amount to repay\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function repayBorrowBehalfInternal(address borrower, uint repayAmount) internal nonReentrant returns (uint) {\n        uint error = accrueInterest();\n        if (error != uint(Error.NO_ERROR)) {\n            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed\n            return fail(Error(error), FailureInfo.REPAY_BEHALF_ACCRUE_INTEREST_FAILED);\n        }\n        // repayBorrowFresh emits repay-borrow-specific logs on errors, so we don\u0027t need to\n        return repayBorrowFresh(msg.sender, borrower, repayAmount);\n    }\n\n    struct RepayBorrowLocalVars {\n        Error err;\n        MathError mathErr;\n        uint repayAmount;\n        uint borrowerIndex;\n        uint accountBorrows;\n        uint accountBorrowsNew;\n        uint totalBorrowsNew;\n    }\n\n    /**\n     * @notice Borrows are repaid by another user (possibly the borrower).\n     * @param payer the account paying off the borrow\n     * @param borrower the account with the debt being payed off\n     * @param repayAmount the amount of undelrying tokens being returned\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function repayBorrowFresh(address payer, address borrower, uint repayAmount) internal returns (uint) {\n        /* Fail if repayBorrow not allowed */\n        uint allowed = comptroller.repayBorrowAllowed(address(this), payer, borrower, repayAmount);\n        if (allowed != 0) {\n            return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.REPAY_BORROW_COMPTROLLER_REJECTION, allowed);\n        }\n\n        /* Verify market\u0027s block number equals current block number */\n        if (accrualBlockNumber != getBlockNumber()) {\n            return fail(Error.MARKET_NOT_FRESH, FailureInfo.REPAY_BORROW_FRESHNESS_CHECK);\n        }\n\n        RepayBorrowLocalVars memory vars;\n\n        /* We remember the original borrowerIndex for verification purposes */\n        vars.borrowerIndex = accountBorrows[borrower].interestIndex;\n\n        /* We fetch the amount the borrower owes, with accumulated interest */\n        (vars.mathErr, vars.accountBorrows) = borrowBalanceStoredInternal(borrower);\n        if (vars.mathErr != MathError.NO_ERROR) {\n            return failOpaque(Error.MATH_ERROR, FailureInfo.REPAY_BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));\n        }\n\n        /* If repayAmount == -1, repayAmount = accountBorrows */\n        if (repayAmount == uint(-1)) {\n            vars.repayAmount = vars.accountBorrows;\n        } else {\n            vars.repayAmount = repayAmount;\n        }\n\n        /* Fail if checkTransferIn fails */\n        vars.err = checkTransferIn(payer, vars.repayAmount);\n        if (vars.err != Error.NO_ERROR) {\n            return fail(vars.err, FailureInfo.REPAY_BORROW_TRANSFER_IN_NOT_POSSIBLE);\n        }\n\n        /*\n         * We calculate the new borrower and total borrow balances, failing on underflow:\n         *  accountBorrowsNew = accountBorrows - repayAmount\n         *  totalBorrowsNew = totalBorrows - repayAmount\n         */\n        (vars.mathErr, vars.accountBorrowsNew) = subUInt(vars.accountBorrows, vars.repayAmount);\n        if (vars.mathErr != MathError.NO_ERROR) {\n            return failOpaque(Error.MATH_ERROR, FailureInfo.REPAY_BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));\n        }\n\n        (vars.mathErr, vars.totalBorrowsNew) = subUInt(totalBorrows, vars.repayAmount);\n        if (vars.mathErr != MathError.NO_ERROR) {\n            return failOpaque(Error.MATH_ERROR, FailureInfo.REPAY_BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));\n        }\n\n        /////////////////////////\n        // EFFECTS \u0026 INTERACTIONS\n        // (No safe failures beyond this point)\n\n        /*\n         * We call doTransferIn for the payer and the repayAmount\n         *  Note: The cToken must handle variations between ERC-20 and ETH underlying.\n         *  On success, the cToken holds an additional repayAmount of cash.\n         *  If doTransferIn fails despite the fact we checked pre-conditions,\n         *   we revert because we can\u0027t be sure if side effects occurred.\n         */\n        vars.err = doTransferIn(payer, vars.repayAmount);\n        require(vars.err == Error.NO_ERROR, \"repay borrow transfer in failed\");\n\n        /* We write the previously calculated values into storage */\n        accountBorrows[borrower].principal = vars.accountBorrowsNew;\n        accountBorrows[borrower].interestIndex = borrowIndex;\n        totalBorrows = vars.totalBorrowsNew;\n\n        /* We emit a RepayBorrow event */\n        emit RepayBorrow(payer, borrower, vars.repayAmount, vars.accountBorrowsNew, vars.totalBorrowsNew);\n\n        /* We call the defense hook */\n        comptroller.repayBorrowVerify(address(this), payer, borrower, vars.repayAmount, vars.borrowerIndex);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n     * @notice The sender liquidates the borrowers collateral.\n     *  The collateral seized is transferred to the liquidator.\n     * @param borrower The borrower of this cToken to be liquidated\n     * @param cTokenCollateral The market in which to seize collateral from the borrower\n     * @param repayAmount The amount of the underlying borrowed asset to repay\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function liquidateBorrowInternal(address borrower, uint repayAmount, CToken cTokenCollateral) internal nonReentrant returns (uint) {\n        uint error = accrueInterest();\n        if (error != uint(Error.NO_ERROR)) {\n            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted liquidation failed\n            return fail(Error(error), FailureInfo.LIQUIDATE_ACCRUE_BORROW_INTEREST_FAILED);\n        }\n\n        error = cTokenCollateral.accrueInterest();\n        if (error != uint(Error.NO_ERROR)) {\n            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted liquidation failed\n            return fail(Error(error), FailureInfo.LIQUIDATE_ACCRUE_COLLATERAL_INTEREST_FAILED);\n        }\n\n        // liquidateBorrowFresh emits borrow-specific logs on errors, so we don\u0027t need to\n        return liquidateBorrowFresh(msg.sender, borrower, repayAmount, cTokenCollateral);\n    }\n\n    /**\n     * @notice The liquidator liquidates the borrowers collateral.\n     *  The collateral seized is transferred to the liquidator.\n     * @param borrower The borrower of this cToken to be liquidated\n     * @param liquidator The address repaying the borrow and seizing collateral\n     * @param cTokenCollateral The market in which to seize collateral from the borrower\n     * @param repayAmount The amount of the underlying borrowed asset to repay\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function liquidateBorrowFresh(address liquidator, address borrower, uint repayAmount, CToken cTokenCollateral) internal returns (uint) {\n        /* Fail if liquidate not allowed */\n        uint allowed = comptroller.liquidateBorrowAllowed(address(this), address(cTokenCollateral), liquidator, borrower, repayAmount);\n        if (allowed != 0) {\n            return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.LIQUIDATE_COMPTROLLER_REJECTION, allowed);\n        }\n\n        /* Verify market\u0027s block number equals current block number */\n        if (accrualBlockNumber != getBlockNumber()) {\n            return fail(Error.MARKET_NOT_FRESH, FailureInfo.LIQUIDATE_FRESHNESS_CHECK);\n        }\n\n        /* Verify cTokenCollateral market\u0027s block number equals current block number */\n        if (cTokenCollateral.accrualBlockNumber() != getBlockNumber()) {\n            return fail(Error.MARKET_NOT_FRESH, FailureInfo.LIQUIDATE_COLLATERAL_FRESHNESS_CHECK);\n        }\n\n        /* Fail if borrower = liquidator */\n        if (borrower == liquidator) {\n            return fail(Error.INVALID_ACCOUNT_PAIR, FailureInfo.LIQUIDATE_LIQUIDATOR_IS_BORROWER);\n        }\n\n        /* Fail if repayAmount = 0 */\n        if (repayAmount == 0) {\n            return fail(Error.INVALID_CLOSE_AMOUNT_REQUESTED, FailureInfo.LIQUIDATE_CLOSE_AMOUNT_IS_ZERO);\n        }\n\n        /* Fail if repayAmount = -1 */\n        if (repayAmount == uint(-1)) {\n            return fail(Error.INVALID_CLOSE_AMOUNT_REQUESTED, FailureInfo.LIQUIDATE_CLOSE_AMOUNT_IS_UINT_MAX);\n        }\n\n        /* We calculate the number of collateral tokens that will be seized */\n        (uint amountSeizeError, uint seizeTokens) = comptroller.liquidateCalculateSeizeTokens(address(this), address(cTokenCollateral), repayAmount);\n        if (amountSeizeError != 0) {\n            return failOpaque(Error.COMPTROLLER_CALCULATION_ERROR, FailureInfo.LIQUIDATE_COMPTROLLER_CALCULATE_AMOUNT_SEIZE_FAILED, amountSeizeError);\n        }\n\n        /* Fail if seizeTokens \u003e borrower collateral token balance */\n        if (seizeTokens \u003e cTokenCollateral.balanceOf(borrower)) {\n            return fail(Error.TOKEN_INSUFFICIENT_BALANCE, FailureInfo.LIQUIDATE_SEIZE_TOO_MUCH);\n        }\n\n        /* Fail if repayBorrow fails */\n        uint repayBorrowError = repayBorrowFresh(liquidator, borrower, repayAmount);\n        if (repayBorrowError != uint(Error.NO_ERROR)) {\n            return fail(Error(repayBorrowError), FailureInfo.LIQUIDATE_REPAY_BORROW_FRESH_FAILED);\n        }\n\n        /* Revert if seize tokens fails (since we cannot be sure of side effects) */\n        uint seizeError = cTokenCollateral.seize(liquidator, borrower, seizeTokens);\n        require(seizeError == uint(Error.NO_ERROR), \"token seizure failed\");\n\n        /* We emit a LiquidateBorrow event */\n        emit LiquidateBorrow(liquidator, borrower, repayAmount, address(cTokenCollateral), seizeTokens);\n\n        /* We call the defense hook */\n        comptroller.liquidateBorrowVerify(address(this), address(cTokenCollateral), liquidator, borrower, repayAmount, seizeTokens);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n     * @notice Transfers collateral tokens (this market) to the liquidator.\n     * @dev Will fail unless called by another cToken during the process of liquidation.\n     *  Its absolutely critical to use msg.sender as the borrowed cToken and not a parameter.\n     * @param liquidator The account receiving seized collateral\n     * @param borrower The account having collateral seized\n     * @param seizeTokens The number of cTokens to seize\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function seize(address liquidator, address borrower, uint seizeTokens) external nonReentrant returns (uint) {\n        /* Fail if seize not allowed */\n        uint allowed = comptroller.seizeAllowed(address(this), msg.sender, liquidator, borrower, seizeTokens);\n        if (allowed != 0) {\n            return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.LIQUIDATE_SEIZE_COMPTROLLER_REJECTION, allowed);\n        }\n\n        /* Fail if borrower = liquidator */\n        if (borrower == liquidator) {\n            return fail(Error.INVALID_ACCOUNT_PAIR, FailureInfo.LIQUIDATE_SEIZE_LIQUIDATOR_IS_BORROWER);\n        }\n\n        MathError mathErr;\n        uint borrowerTokensNew;\n        uint liquidatorTokensNew;\n\n        /*\n         * We calculate the new borrower and liquidator token balances, failing on underflow/overflow:\n         *  borrowerTokensNew = accountTokens[borrower] - seizeTokens\n         *  liquidatorTokensNew = accountTokens[liquidator] + seizeTokens\n         */\n        (mathErr, borrowerTokensNew) = subUInt(accountTokens[borrower], seizeTokens);\n        if (mathErr != MathError.NO_ERROR) {\n            return failOpaque(Error.MATH_ERROR, FailureInfo.LIQUIDATE_SEIZE_BALANCE_DECREMENT_FAILED, uint(mathErr));\n        }\n\n        (mathErr, liquidatorTokensNew) = addUInt(accountTokens[liquidator], seizeTokens);\n        if (mathErr != MathError.NO_ERROR) {\n            return failOpaque(Error.MATH_ERROR, FailureInfo.LIQUIDATE_SEIZE_BALANCE_INCREMENT_FAILED, uint(mathErr));\n        }\n\n        /////////////////////////\n        // EFFECTS \u0026 INTERACTIONS\n        // (No safe failures beyond this point)\n\n        /* We write the previously calculated values into storage */\n        accountTokens[borrower] = borrowerTokensNew;\n        accountTokens[liquidator] = liquidatorTokensNew;\n\n        /* Emit a Transfer event */\n        emit Transfer(borrower, liquidator, seizeTokens);\n\n        /* We call the defense hook */\n        comptroller.seizeVerify(address(this), msg.sender, liquidator, borrower, seizeTokens);\n\n        return uint(Error.NO_ERROR);\n    }\n\n\n    /*** Admin Functions ***/\n\n    /**\n      * @notice Begins transfer of admin rights. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.\n      * @dev Admin function to begin change of admin. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.\n      * @param newPendingAdmin New pending admin.\n      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n      *\n      * TODO: Should we add a second arg to verify, like a checksum of `newAdmin` address?\n      */\n    function _setPendingAdmin(address payable newPendingAdmin) external returns (uint) {\n        // Check caller = admin\n        if (msg.sender != admin) {\n            return fail(Error.UNAUTHORIZED, FailureInfo.SET_PENDING_ADMIN_OWNER_CHECK);\n        }\n\n        // Save current value, if any, for inclusion in log\n        address oldPendingAdmin = pendingAdmin;\n\n        // Store pendingAdmin with value newPendingAdmin\n        pendingAdmin = newPendingAdmin;\n\n        // Emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin)\n        emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n      * @notice Accepts transfer of admin rights. msg.sender must be pendingAdmin\n      * @dev Admin function for pending admin to accept role and update admin\n      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n      */\n    function _acceptAdmin() external returns (uint) {\n        // Check caller is pendingAdmin and pendingAdmin ≠ address(0)\n        if (msg.sender != pendingAdmin || msg.sender == address(0)) {\n            return fail(Error.UNAUTHORIZED, FailureInfo.ACCEPT_ADMIN_PENDING_ADMIN_CHECK);\n        }\n\n        // Save current values for inclusion in log\n        address oldAdmin = admin;\n        address oldPendingAdmin = pendingAdmin;\n\n        // Store admin with value pendingAdmin\n        admin = pendingAdmin;\n\n        // Clear the pending value\n        pendingAdmin = address(0);\n\n        emit NewAdmin(oldAdmin, admin);\n        emit NewPendingAdmin(oldPendingAdmin, pendingAdmin);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n      * @notice Sets a new comptroller for the market\n      * @dev Admin function to set a new comptroller\n      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n      */\n    function _setComptroller(ComptrollerInterface newComptroller) public returns (uint) {\n        // Check caller is admin\n        if (msg.sender != admin) {\n            return fail(Error.UNAUTHORIZED, FailureInfo.SET_COMPTROLLER_OWNER_CHECK);\n        }\n\n        ComptrollerInterface oldComptroller = comptroller;\n        // Ensure invoke comptroller.isComptroller() returns true\n        require(newComptroller.isComptroller(), \"marker method returned false\");\n\n        // Set market\u0027s comptroller to newComptroller\n        comptroller = newComptroller;\n\n        // Emit NewComptroller(oldComptroller, newComptroller)\n        emit NewComptroller(oldComptroller, newComptroller);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n      * @notice accrues interest and sets a new reserve factor for the protocol using _setReserveFactorFresh\n      * @dev Admin function to accrue interest and set a new reserve factor\n      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n      */\n    function _setReserveFactor(uint newReserveFactorMantissa) external nonReentrant returns (uint) {\n        uint error = accrueInterest();\n        if (error != uint(Error.NO_ERROR)) {\n            // accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted reserve factor change failed.\n            return fail(Error(error), FailureInfo.SET_RESERVE_FACTOR_ACCRUE_INTEREST_FAILED);\n        }\n        // _setReserveFactorFresh emits reserve-factor-specific logs on errors, so we don\u0027t need to.\n        return _setReserveFactorFresh(newReserveFactorMantissa);\n    }\n\n    /**\n      * @notice Sets a new reserve factor for the protocol (*requires fresh interest accrual)\n      * @dev Admin function to set a new reserve factor\n      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n      */\n    function _setReserveFactorFresh(uint newReserveFactorMantissa) internal returns (uint) {\n        // Check caller is admin\n        if (msg.sender != admin) {\n            return fail(Error.UNAUTHORIZED, FailureInfo.SET_RESERVE_FACTOR_ADMIN_CHECK);\n        }\n\n        // Verify market\u0027s block number equals current block number\n        if (accrualBlockNumber != getBlockNumber()) {\n            // TODO: static_assert + no error code?\n            return fail(Error.MARKET_NOT_FRESH, FailureInfo.SET_RESERVE_FACTOR_FRESH_CHECK);\n        }\n\n        // Check newReserveFactor ≤ maxReserveFactor\n        if (newReserveFactorMantissa \u003e reserveFactorMaxMantissa) {\n            return fail(Error.BAD_INPUT, FailureInfo.SET_RESERVE_FACTOR_BOUNDS_CHECK);\n        }\n\n        uint oldReserveFactorMantissa = reserveFactorMantissa;\n        reserveFactorMantissa = newReserveFactorMantissa;\n\n        emit NewReserveFactor(oldReserveFactorMantissa, newReserveFactorMantissa);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n     * @notice Accrues interest and reduces reserves by transferring to admin\n     * @param reduceAmount Amount of reduction to reserves\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function _reduceReserves(uint reduceAmount) external nonReentrant returns (uint) {\n        uint error = accrueInterest();\n        if (error != uint(Error.NO_ERROR)) {\n            // accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted reduce reserves failed.\n            return fail(Error(error), FailureInfo.REDUCE_RESERVES_ACCRUE_INTEREST_FAILED);\n        }\n        // _reduceReservesFresh emits reserve-reduction-specific logs on errors, so we don\u0027t need to.\n        return _reduceReservesFresh(reduceAmount);\n    }\n\n    /**\n     * @notice Reduces reserves by transferring to admin\n     * @dev Requires fresh interest accrual\n     * @param reduceAmount Amount of reduction to reserves\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function _reduceReservesFresh(uint reduceAmount) internal returns (uint) {\n        Error err;\n        // totalReserves - reduceAmount\n        uint totalReservesNew;\n\n        // Check caller is admin\n        if (msg.sender != admin) {\n            return fail(Error.UNAUTHORIZED, FailureInfo.REDUCE_RESERVES_ADMIN_CHECK);\n        }\n\n        // We fail gracefully unless market\u0027s block number equals current block number\n        if (accrualBlockNumber != getBlockNumber()) {\n            // TODO: static_assert + no error code?\n            return fail(Error.MARKET_NOT_FRESH, FailureInfo.REDUCE_RESERVES_FRESH_CHECK);\n        }\n\n        // Fail gracefully if protocol has insufficient underlying cash\n        if (getCashPrior() \u003c reduceAmount) {\n            return fail(Error.TOKEN_INSUFFICIENT_CASH, FailureInfo.REDUCE_RESERVES_CASH_NOT_AVAILABLE);\n        }\n\n        // Check reduceAmount ≤ reserves[n] (totalReserves)\n        // TODO: I\u0027m following the spec literally here but I think we should we just use SafeMath instead and fail on an error (which would be underflow)\n        if (reduceAmount \u003e totalReserves) {\n            return fail(Error.BAD_INPUT, FailureInfo.REDUCE_RESERVES_VALIDATION);\n        }\n\n        /////////////////////////\n        // EFFECTS \u0026 INTERACTIONS\n        // (No safe failures beyond this point)\n\n        totalReservesNew = totalReserves - reduceAmount;\n        // We checked reduceAmount \u003c= totalReserves above, so this should never revert.\n        require(totalReservesNew \u003c= totalReserves, \"reduce reserves unexpected underflow\");\n\n        // Store reserves[n+1] = reserves[n] - reduceAmount\n        totalReserves = totalReservesNew;\n\n        // invoke doTransferOut(reduceAmount, admin)\n        err = doTransferOut(admin, reduceAmount);\n        // we revert on the failure of this command\n        require(err == Error.NO_ERROR, \"reduce reserves transfer out failed\");\n\n        emit ReservesReduced(admin, reduceAmount, totalReservesNew);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n     * @notice accrues interest and updates the interest rate model using _setInterestRateModelFresh\n     * @dev Admin function to accrue interest and update the interest rate model\n     * @param newInterestRateModel the new interest rate model to use\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function _setInterestRateModel(InterestRateModel newInterestRateModel) public returns (uint) {\n        uint error = accrueInterest();\n        if (error != uint(Error.NO_ERROR)) {\n            // accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted change of interest rate model failed\n            return fail(Error(error), FailureInfo.SET_INTEREST_RATE_MODEL_ACCRUE_INTEREST_FAILED);\n        }\n        // _setInterestRateModelFresh emits interest-rate-model-update-specific logs on errors, so we don\u0027t need to.\n        return _setInterestRateModelFresh(newInterestRateModel);\n    }\n\n    /**\n     * @notice updates the interest rate model (*requires fresh interest accrual)\n     * @dev Admin function to update the interest rate model\n     * @param newInterestRateModel the new interest rate model to use\n     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n     */\n    function _setInterestRateModelFresh(InterestRateModel newInterestRateModel) internal returns (uint) {\n\n        // Used to store old model for use in the event that is emitted on success\n        InterestRateModel oldInterestRateModel;\n\n        // Check caller is admin\n        if (msg.sender != admin) {\n            return fail(Error.UNAUTHORIZED, FailureInfo.SET_INTEREST_RATE_MODEL_OWNER_CHECK);\n        }\n\n        // We fail gracefully unless market\u0027s block number equals current block number\n        if (accrualBlockNumber != getBlockNumber()) {\n            // TODO: static_assert + no error code?\n            return fail(Error.MARKET_NOT_FRESH, FailureInfo.SET_INTEREST_RATE_MODEL_FRESH_CHECK);\n        }\n\n        // Track the market\u0027s current interest rate model\n        oldInterestRateModel = interestRateModel;\n\n        // Ensure invoke newInterestRateModel.isInterestRateModel() returns true\n        require(newInterestRateModel.isInterestRateModel(), \"marker method returned false\");\n\n        // Set the interest rate model to newInterestRateModel\n        interestRateModel = newInterestRateModel;\n\n        // Emit NewMarketInterestRateModel(oldInterestRateModel, newInterestRateModel)\n        emit NewMarketInterestRateModel(oldInterestRateModel, newInterestRateModel);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /*** Safe Token ***/\n\n    /**\n     * @notice Gets balance of this contract in terms of the underlying\n     * @dev This excludes the value of the current message, if any\n     * @return The quantity of underlying owned by this contract\n     */\n    function getCashPrior() internal view returns (uint);\n\n    /**\n     * @dev Checks whether or not there is sufficient allowance for this contract to move amount from `from` and\n     *      whether or not `from` has a balance of at least `amount`. Does NOT do a transfer.\n     */\n    function checkTransferIn(address from, uint amount) internal view returns (Error);\n\n    /**\n     * @dev Performs a transfer in, ideally returning an explanatory error code upon failure rather than reverting.\n     *  If caller has not called `checkTransferIn`, this may revert due to insufficient balance or insufficient allowance.\n     *  If caller has called `checkTransferIn` successfully, this should not revert in normal conditions.\n     */\n    function doTransferIn(address from, uint amount) internal returns (Error);\n\n    /**\n     * @dev Performs a transfer out, ideally returning an explanatory error code upon failure tather than reverting.\n     *  If caller has not called checked protocol\u0027s balance, may revert due to insufficient cash held in the contract.\n     *  If caller has checked protocol\u0027s balance, and verified it is \u003e= amount, this should not revert in normal conditions.\n     */\n    function doTransferOut(address payable to, uint amount) internal returns (Error);\n}\n"},"EIP20Interface.sol":{"content":"pragma solidity ^0.5.8;\n\n/**\n * @title ERC 20 Token Standard Interface\n *  https://eips.ethereum.org/EIPS/eip-20\n */\ninterface EIP20Interface {\n\n    /**\n      * @notice Get the total number of tokens in circulation\n      * @return The supply of tokens\n      */\n    function totalSupply() external view returns (uint256);\n\n    /**\n     * @notice Gets the balance of the specified address\n     * @param owner The address from which the balance will be retrieved\n     * @return The balance\n     */\n    function balanceOf(address owner) external view returns (uint256 balance);\n\n    /**\n      * @notice Transfer `amount` tokens from `msg.sender` to `dst`\n      * @param dst The address of the destination account\n      * @param amount The number of tokens to transfer\n      * @return Whether or not the transfer succeeded\n      */\n    function transfer(address dst, uint256 amount) external returns (bool success);\n\n    /**\n      * @notice Transfer `amount` tokens from `src` to `dst`\n      * @param src The address of the source account\n      * @param dst The address of the destination account\n      * @param amount The number of tokens to transfer\n      * @return Whether or not the transfer succeeded\n      */\n    function transferFrom(address src, address dst, uint256 amount) external returns (bool success);\n\n    /**\n      * @notice Approve `spender` to transfer up to `amount` from `src`\n      * @dev This will overwrite the approval amount for `spender`\n      *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)\n      * @param spender The address of the account which may transfer tokens\n      * @param amount The number of tokens that are approved (-1 means infinite)\n      * @return Whether or not the approval succeeded\n      */\n    function approve(address spender, uint256 amount) external returns (bool success);\n\n    /**\n      * @notice Get the current allowance from `owner` for `spender`\n      * @param owner The address of the account which owns the tokens to be spent\n      * @param spender The address of the account which may transfer tokens\n      * @return The number of tokens allowed to be spent (-1 means infinite)\n      */\n    function allowance(address owner, address spender) external view returns (uint256 remaining);\n\n    event Transfer(address indexed from, address indexed to, uint256 amount);\n    event Approval(address indexed owner, address indexed spender, uint256 amount);\n}\n"},"EIP20NonStandardInterface.sol":{"content":"pragma solidity ^0.5.8;\n\n/**\n * @title EIP20NonStandardInterface\n * @dev Version of ERC20 with no return values for `transfer` and `transferFrom`\n *  See https://medium.com/coinmonks/missing-return-value-bug-at-least-130-tokens-affected-d67bf08521ca\n */\ninterface EIP20NonStandardInterface {\n\n    /**\n     * @notice Get the total number of tokens in circulation\n     * @return The supply of tokens\n     */\n    function totalSupply() external view returns (uint256);\n\n    /**\n     * @notice Gets the balance of the specified address\n     * @param owner The address from which the balance will be retrieved\n     * @return The balance\n     */\n    function balanceOf(address owner) external view returns (uint256 balance);\n\n    ///\n    /// !!!!!!!!!!!!!!\n    /// !!! NOTICE !!! `transfer` does not return a value, in violation of the ERC-20 specification\n    /// !!!!!!!!!!!!!!\n    ///\n\n    /**\n      * @notice Transfer `amount` tokens from `msg.sender` to `dst`\n      * @param dst The address of the destination account\n      * @param amount The number of tokens to transfer\n      */\n    function transfer(address dst, uint256 amount) external;\n\n    ///\n    /// !!!!!!!!!!!!!!\n    /// !!! NOTICE !!! `transferFrom` does not return a value, in violation of the ERC-20 specification\n    /// !!!!!!!!!!!!!!\n    ///\n\n    /**\n      * @notice Transfer `amount` tokens from `src` to `dst`\n      * @param src The address of the source account\n      * @param dst The address of the destination account\n      * @param amount The number of tokens to transfer\n      */\n    function transferFrom(address src, address dst, uint256 amount) external;\n\n    /**\n      * @notice Approve `spender` to transfer up to `amount` from `src`\n      * @dev This will overwrite the approval amount for `spender`\n      *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)\n      * @param spender The address of the account which may transfer tokens\n      * @param amount The number of tokens that are approved\n      * @return Whether or not the approval succeeded\n      */\n    function approve(address spender, uint256 amount) external returns (bool success);\n\n    /**\n      * @notice Get the current allowance from `owner` for `spender`\n      * @param owner The address of the account which owns the tokens to be spent\n      * @param spender The address of the account which may transfer tokens\n      * @return The number of tokens allowed to be spent\n      */\n    function allowance(address owner, address spender) external view returns (uint256 remaining);\n\n    event Transfer(address indexed from, address indexed to, uint256 amount);\n    event Approval(address indexed owner, address indexed spender, uint256 amount);\n}\n"},"ErrorReporter.sol":{"content":"pragma solidity ^0.5.8;\n\ncontract ComptrollerErrorReporter {\n    enum Error {\n        NO_ERROR,\n        UNAUTHORIZED,\n        COMPTROLLER_MISMATCH,\n        INSUFFICIENT_SHORTFALL,\n        INSUFFICIENT_LIQUIDITY,\n        INVALID_CLOSE_FACTOR,\n        INVALID_COLLATERAL_FACTOR,\n        INVALID_LIQUIDATION_INCENTIVE,\n        MARKET_NOT_ENTERED,\n        MARKET_NOT_LISTED,\n        MARKET_ALREADY_LISTED,\n        MATH_ERROR,\n        NONZERO_BORROW_BALANCE,\n        PRICE_ERROR,\n        REJECTION,\n        SNAPSHOT_ERROR,\n        TOO_MANY_ASSETS,\n        TOO_MUCH_REPAY\n    }\n\n    enum FailureInfo {\n        ACCEPT_ADMIN_PENDING_ADMIN_CHECK,\n        ACCEPT_PENDING_IMPLEMENTATION_ADDRESS_CHECK,\n        EXIT_MARKET_BALANCE_OWED,\n        EXIT_MARKET_REJECTION,\n        SET_CLOSE_FACTOR_OWNER_CHECK,\n        SET_CLOSE_FACTOR_VALIDATION,\n        SET_COLLATERAL_FACTOR_OWNER_CHECK,\n        SET_COLLATERAL_FACTOR_NO_EXISTS,\n        SET_COLLATERAL_FACTOR_VALIDATION,\n        SET_COLLATERAL_FACTOR_WITHOUT_PRICE,\n        SET_IMPLEMENTATION_OWNER_CHECK,\n        SET_LIQUIDATION_INCENTIVE_OWNER_CHECK,\n        SET_LIQUIDATION_INCENTIVE_VALIDATION,\n        SET_MAX_ASSETS_OWNER_CHECK,\n        SET_PENDING_ADMIN_OWNER_CHECK,\n        SET_PENDING_IMPLEMENTATION_OWNER_CHECK,\n        SET_PRICE_ORACLE_OWNER_CHECK,\n        SUPPORT_MARKET_EXISTS,\n        SUPPORT_MARKET_OWNER_CHECK,\n        ZUNUSED\n    }\n\n    /**\n      * @dev `error` corresponds to enum Error; `info` corresponds to enum FailureInfo, and `detail` is an arbitrary\n      * contract-specific code that enables us to report opaque error codes from upgradeable contracts.\n      **/\n    event Failure(uint error, uint info, uint detail);\n\n    /**\n      * @dev use this when reporting a known error from the money market or a non-upgradeable collaborator\n      */\n    function fail(Error err, FailureInfo info) internal returns (uint) {\n        emit Failure(uint(err), uint(info), 0);\n\n        return uint(err);\n    }\n\n    /**\n      * @dev use this when reporting an opaque error from an upgradeable collaborator contract\n      */\n    function failOpaque(Error err, FailureInfo info, uint opaqueError) internal returns (uint) {\n        emit Failure(uint(err), uint(info), opaqueError);\n\n        return uint(err);\n    }\n}\n\ncontract TokenErrorReporter {\n    enum Error {\n        NO_ERROR,\n        UNAUTHORIZED,\n        BAD_INPUT,\n        COMPTROLLER_REJECTION,\n        COMPTROLLER_CALCULATION_ERROR,\n        INTEREST_RATE_MODEL_ERROR,\n        INVALID_ACCOUNT_PAIR,\n        INVALID_CLOSE_AMOUNT_REQUESTED,\n        INVALID_COLLATERAL_FACTOR,\n        MATH_ERROR,\n        MARKET_NOT_FRESH,\n        MARKET_NOT_LISTED,\n        TOKEN_INSUFFICIENT_ALLOWANCE,\n        TOKEN_INSUFFICIENT_BALANCE,\n        TOKEN_INSUFFICIENT_CASH,\n        TOKEN_TRANSFER_IN_FAILED,\n        TOKEN_TRANSFER_OUT_FAILED\n    }\n\n    /*\n     * Note: FailureInfo (but not Error) is kept in alphabetical order\n     *       This is because FailureInfo grows significantly faster, and\n     *       the order of Error has some meaning, while the order of FailureInfo\n     *       is entirely arbitrary.\n     */\n    enum FailureInfo {\n        ACCEPT_ADMIN_PENDING_ADMIN_CHECK,\n        ACCRUE_INTEREST_ACCUMULATED_INTEREST_CALCULATION_FAILED,\n        ACCRUE_INTEREST_BORROW_RATE_CALCULATION_FAILED,\n        ACCRUE_INTEREST_NEW_BORROW_INDEX_CALCULATION_FAILED,\n        ACCRUE_INTEREST_NEW_TOTAL_BORROWS_CALCULATION_FAILED,\n        ACCRUE_INTEREST_NEW_TOTAL_RESERVES_CALCULATION_FAILED,\n        ACCRUE_INTEREST_SIMPLE_INTEREST_FACTOR_CALCULATION_FAILED,\n        BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED,\n        BORROW_ACCRUE_INTEREST_FAILED,\n        BORROW_CASH_NOT_AVAILABLE,\n        BORROW_FRESHNESS_CHECK,\n        BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED,\n        BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED,\n        BORROW_MARKET_NOT_LISTED,\n        BORROW_COMPTROLLER_REJECTION,\n        LIQUIDATE_ACCRUE_BORROW_INTEREST_FAILED,\n        LIQUIDATE_ACCRUE_COLLATERAL_INTEREST_FAILED,\n        LIQUIDATE_COLLATERAL_FRESHNESS_CHECK,\n        LIQUIDATE_COMPTROLLER_REJECTION,\n        LIQUIDATE_COMPTROLLER_CALCULATE_AMOUNT_SEIZE_FAILED,\n        LIQUIDATE_CLOSE_AMOUNT_IS_UINT_MAX,\n        LIQUIDATE_CLOSE_AMOUNT_IS_ZERO,\n        LIQUIDATE_FRESHNESS_CHECK,\n        LIQUIDATE_LIQUIDATOR_IS_BORROWER,\n        LIQUIDATE_REPAY_BORROW_FRESH_FAILED,\n        LIQUIDATE_SEIZE_BALANCE_INCREMENT_FAILED,\n        LIQUIDATE_SEIZE_BALANCE_DECREMENT_FAILED,\n        LIQUIDATE_SEIZE_COMPTROLLER_REJECTION,\n        LIQUIDATE_SEIZE_LIQUIDATOR_IS_BORROWER,\n        LIQUIDATE_SEIZE_TOO_MUCH,\n        MINT_ACCRUE_INTEREST_FAILED,\n        MINT_COMPTROLLER_REJECTION,\n        MINT_EXCHANGE_CALCULATION_FAILED,\n        MINT_EXCHANGE_RATE_READ_FAILED,\n        MINT_FRESHNESS_CHECK,\n        MINT_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED,\n        MINT_NEW_TOTAL_SUPPLY_CALCULATION_FAILED,\n        MINT_TRANSFER_IN_FAILED,\n        MINT_TRANSFER_IN_NOT_POSSIBLE,\n        REDEEM_ACCRUE_INTEREST_FAILED,\n        REDEEM_COMPTROLLER_REJECTION,\n        REDEEM_EXCHANGE_TOKENS_CALCULATION_FAILED,\n        REDEEM_EXCHANGE_AMOUNT_CALCULATION_FAILED,\n        REDEEM_EXCHANGE_RATE_READ_FAILED,\n        REDEEM_FRESHNESS_CHECK,\n        REDEEM_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED,\n        REDEEM_NEW_TOTAL_SUPPLY_CALCULATION_FAILED,\n        REDEEM_TRANSFER_OUT_NOT_POSSIBLE,\n        REDUCE_RESERVES_ACCRUE_INTEREST_FAILED,\n        REDUCE_RESERVES_ADMIN_CHECK,\n        REDUCE_RESERVES_CASH_NOT_AVAILABLE,\n        REDUCE_RESERVES_FRESH_CHECK,\n        REDUCE_RESERVES_VALIDATION,\n        REPAY_BEHALF_ACCRUE_INTEREST_FAILED,\n        REPAY_BORROW_ACCRUE_INTEREST_FAILED,\n        REPAY_BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED,\n        REPAY_BORROW_COMPTROLLER_REJECTION,\n        REPAY_BORROW_FRESHNESS_CHECK,\n        REPAY_BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED,\n        REPAY_BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED,\n        REPAY_BORROW_TRANSFER_IN_NOT_POSSIBLE,\n        SET_COLLATERAL_FACTOR_OWNER_CHECK,\n        SET_COLLATERAL_FACTOR_VALIDATION,\n        SET_COMPTROLLER_OWNER_CHECK,\n        SET_INTEREST_RATE_MODEL_ACCRUE_INTEREST_FAILED,\n        SET_INTEREST_RATE_MODEL_FRESH_CHECK,\n        SET_INTEREST_RATE_MODEL_OWNER_CHECK,\n        SET_MAX_ASSETS_OWNER_CHECK,\n        SET_ORACLE_MARKET_NOT_LISTED,\n        SET_PENDING_ADMIN_OWNER_CHECK,\n        SET_RESERVE_FACTOR_ACCRUE_INTEREST_FAILED,\n        SET_RESERVE_FACTOR_ADMIN_CHECK,\n        SET_RESERVE_FACTOR_FRESH_CHECK,\n        SET_RESERVE_FACTOR_BOUNDS_CHECK,\n        TRANSFER_COMPTROLLER_REJECTION,\n        TRANSFER_NOT_ALLOWED,\n        TRANSFER_NOT_ENOUGH,\n        TRANSFER_TOO_MUCH\n    }\n\n    /**\n      * @dev `error` corresponds to enum Error; `info` corresponds to enum FailureInfo, and `detail` is an arbitrary\n      * contract-specific code that enables us to report opaque error codes from upgradeable contracts.\n      **/\n    event Failure(uint error, uint info, uint detail);\n\n    /**\n      * @dev use this when reporting a known error from the money market or a non-upgradeable collaborator\n      */\n    function fail(Error err, FailureInfo info) internal returns (uint) {\n        emit Failure(uint(err), uint(info), 0);\n\n        return uint(err);\n    }\n\n    /**\n      * @dev use this when reporting an opaque error from an upgradeable collaborator contract\n      */\n    function failOpaque(Error err, FailureInfo info, uint opaqueError) internal returns (uint) {\n        emit Failure(uint(err), uint(info), opaqueError);\n\n        return uint(err);\n    }\n}\n"},"Exponential.sol":{"content":"pragma solidity ^0.5.8;\n\nimport \"./CarefulMath.sol\";\n\n/**\n * @title Exponential module for storing fixed-decision decimals\n * @author Compound\n * @notice Exp is a struct which stores decimals with a fixed precision of 18 decimal places.\n *         Thus, if we wanted to store the 5.1, mantissa would store 5.1e18. That is:\n *         `Exp({mantissa: 5100000000000000000})`.\n */\ncontract Exponential is CarefulMath {\n    uint constant expScale = 1e18;\n    uint constant halfExpScale = expScale/2;\n    uint constant mantissaOne = expScale;\n\n    struct Exp {\n        uint mantissa;\n    }\n\n    /**\n     * @dev Creates an exponential from numerator and denominator values.\n     *      Note: Returns an error if (`num` * 10e18) \u003e MAX_INT,\n     *            or if `denom` is zero.\n     */\n    function getExp(uint num, uint denom) pure internal returns (MathError, Exp memory) {\n        (MathError err0, uint scaledNumerator) = mulUInt(num, expScale);\n        if (err0 != MathError.NO_ERROR) {\n            return (err0, Exp({mantissa: 0}));\n        }\n\n        (MathError err1, uint rational) = divUInt(scaledNumerator, denom);\n        if (err1 != MathError.NO_ERROR) {\n            return (err1, Exp({mantissa: 0}));\n        }\n\n        return (MathError.NO_ERROR, Exp({mantissa: rational}));\n    }\n\n    /**\n     * @dev Adds two exponentials, returning a new exponential.\n     */\n    function addExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {\n        (MathError error, uint result) = addUInt(a.mantissa, b.mantissa);\n\n        return (error, Exp({mantissa: result}));\n    }\n\n    /**\n     * @dev Subtracts two exponentials, returning a new exponential.\n     */\n    function subExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {\n        (MathError error, uint result) = subUInt(a.mantissa, b.mantissa);\n\n        return (error, Exp({mantissa: result}));\n    }\n\n    /**\n     * @dev Multiply an Exp by a scalar, returning a new Exp.\n     */\n    function mulScalar(Exp memory a, uint scalar) pure internal returns (MathError, Exp memory) {\n        (MathError err0, uint scaledMantissa) = mulUInt(a.mantissa, scalar);\n        if (err0 != MathError.NO_ERROR) {\n            return (err0, Exp({mantissa: 0}));\n        }\n\n        return (MathError.NO_ERROR, Exp({mantissa: scaledMantissa}));\n    }\n\n    /**\n     * @dev Multiply an Exp by a scalar, then truncate to return an unsigned integer.\n     */\n    function mulScalarTruncate(Exp memory a, uint scalar) pure internal returns (MathError, uint) {\n        (MathError err, Exp memory product) = mulScalar(a, scalar);\n        if (err != MathError.NO_ERROR) {\n            return (err, 0);\n        }\n\n        return (MathError.NO_ERROR, truncate(product));\n    }\n\n    /**\n     * @dev Multiply an Exp by a scalar, truncate, then add an to an unsigned integer, returning an unsigned integer.\n     */\n    function mulScalarTruncateAddUInt(Exp memory a, uint scalar, uint addend) pure internal returns (MathError, uint) {\n        (MathError err, Exp memory product) = mulScalar(a, scalar);\n        if (err != MathError.NO_ERROR) {\n            return (err, 0);\n        }\n\n        return addUInt(truncate(product), addend);\n    }\n\n    /**\n     * @dev Divide an Exp by a scalar, returning a new Exp.\n     */\n    function divScalar(Exp memory a, uint scalar) pure internal returns (MathError, Exp memory) {\n        (MathError err0, uint descaledMantissa) = divUInt(a.mantissa, scalar);\n        if (err0 != MathError.NO_ERROR) {\n            return (err0, Exp({mantissa: 0}));\n        }\n\n        return (MathError.NO_ERROR, Exp({mantissa: descaledMantissa}));\n    }\n\n    /**\n     * @dev Divide a scalar by an Exp, returning a new Exp.\n     */\n    function divScalarByExp(uint scalar, Exp memory divisor) pure internal returns (MathError, Exp memory) {\n        /*\n          We are doing this as:\n          getExp(mulUInt(expScale, scalar), divisor.mantissa)\n\n          How it works:\n          Exp = a / b;\n          Scalar = s;\n          `s / (a / b)` = `b * s / a` and since for an Exp `a = mantissa, b = expScale`\n        */\n        (MathError err0, uint numerator) = mulUInt(expScale, scalar);\n        if (err0 != MathError.NO_ERROR) {\n            return (err0, Exp({mantissa: 0}));\n        }\n        return getExp(numerator, divisor.mantissa);\n    }\n\n    /**\n     * @dev Divide a scalar by an Exp, then truncate to return an unsigned integer.\n     */\n    function divScalarByExpTruncate(uint scalar, Exp memory divisor) pure internal returns (MathError, uint) {\n        (MathError err, Exp memory fraction) = divScalarByExp(scalar, divisor);\n        if (err != MathError.NO_ERROR) {\n            return (err, 0);\n        }\n\n        return (MathError.NO_ERROR, truncate(fraction));\n    }\n\n    /**\n     * @dev Multiplies two exponentials, returning a new exponential.\n     */\n    function mulExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {\n\n        (MathError err0, uint doubleScaledProduct) = mulUInt(a.mantissa, b.mantissa);\n        if (err0 != MathError.NO_ERROR) {\n            return (err0, Exp({mantissa: 0}));\n        }\n\n        // We add half the scale before dividing so that we get rounding instead of truncation.\n        //  See \"Listing 6\" and text above it at https://accu.org/index.php/journals/1717\n        // Without this change, a result like 6.6...e-19 will be truncated to 0 instead of being rounded to 1e-18.\n        (MathError err1, uint doubleScaledProductWithHalfScale) = addUInt(halfExpScale, doubleScaledProduct);\n        if (err1 != MathError.NO_ERROR) {\n            return (err1, Exp({mantissa: 0}));\n        }\n\n        (MathError err2, uint product) = divUInt(doubleScaledProductWithHalfScale, expScale);\n        // The only error `div` can return is MathError.DIVISION_BY_ZERO but we control `expScale` and it is not zero.\n        assert(err2 == MathError.NO_ERROR);\n\n        return (MathError.NO_ERROR, Exp({mantissa: product}));\n    }\n\n    /**\n     * @dev Multiplies two exponentials given their mantissas, returning a new exponential.\n     */\n    function mulExp(uint a, uint b) pure internal returns (MathError, Exp memory) {\n        return mulExp(Exp({mantissa: a}), Exp({mantissa: b}));\n    }\n\n    /**\n     * @dev Multiplies three exponentials, returning a new exponential.\n     */\n    function mulExp3(Exp memory a, Exp memory b, Exp memory c) pure internal returns (MathError, Exp memory) {\n        (MathError err, Exp memory ab) = mulExp(a, b);\n        if (err != MathError.NO_ERROR) {\n            return (err, ab);\n        }\n        return mulExp(ab, c);\n    }\n\n    /**\n     * @dev Divides two exponentials, returning a new exponential.\n     *     (a/scale) / (b/scale) = (a/scale) * (scale/b) = a/b,\n     *  which we can scale as an Exp by calling getExp(a.mantissa, b.mantissa)\n     */\n    function divExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {\n        return getExp(a.mantissa, b.mantissa);\n    }\n\n    /**\n     * @dev Truncates the given exp to a whole number value.\n     *      For example, truncate(Exp{mantissa: 15 * expScale}) = 15\n     */\n    function truncate(Exp memory exp) pure internal returns (uint) {\n        // Note: We are not using careful math here as we\u0027re performing a division that cannot fail\n        return exp.mantissa / expScale;\n    }\n\n    /**\n     * @dev Checks if first Exp is less than second Exp.\n     */\n    function lessThanExp(Exp memory left, Exp memory right) pure internal returns (bool) {\n        return left.mantissa \u003c right.mantissa; //TODO: Add some simple tests and this in another PR yo.\n    }\n\n    /**\n     * @dev Checks if left Exp \u003c= right Exp.\n     */\n    function lessThanOrEqualExp(Exp memory left, Exp memory right) pure internal returns (bool) {\n        return left.mantissa \u003c= right.mantissa;\n    }\n\n    /**\n     * @dev returns true if Exp is exactly zero\n     */\n    function isZeroExp(Exp memory value) pure internal returns (bool) {\n        return value.mantissa == 0;\n    }\n}\n"},"InterestRateModel.sol":{"content":"pragma solidity ^0.5.8;\n\n/**\n  * @title The Compound InterestRateModel Interface\n  * @author Compound\n  * @notice Any interest rate model should derive from this contract.\n  * @dev These functions are specifically not marked `pure` as implementations of this\n  *      contract may read from storage variables.\n  */\ninterface InterestRateModel {\n    /**\n      * @notice Gets the current borrow interest rate based on the given asset, total cash, total borrows\n      *         and total reserves.\n      * @dev The return value should be scaled by 1e18, thus a return value of\n      *      `(true, 1000000000000)` implies an interest rate of 0.000001 or 0.0001% *per block*.\n      * @param cash The total cash of the underlying asset in the CToken\n      * @param borrows The total borrows of the underlying asset in the CToken\n      * @param reserves The total reserves of the underlying asset in the CToken\n      * @return Success or failure and the borrow interest rate per block scaled by 10e18\n      */\n    function getBorrowRate(uint cash, uint borrows, uint reserves) external view returns (uint, uint);\n\n    /**\n      * @notice Marker function used for light validation when updating the interest rate model of a market\n      * @dev Marker function used for light validation when updating the interest rate model of a market. Implementations should simply return true.\n      * @return Success or failure\n      */\n    function isInterestRateModel() external view returns (bool);\n}"},"Maximillion.sol":{"content":"pragma solidity ^0.5.8;\n\nimport \"./CEther.sol\";\n\n/**\n * @title Compound\u0027s Maximillion Contract\n * @author Compound\n */\ncontract Maximillion {\n    /**\n     * @notice The default cEther market to repay in\n     */\n    CEther public cEther;\n\n    /**\n     * @notice Construct a Maximillion to repay max in a CEther market\n     */\n    constructor(CEther cEther_) public {\n        cEther = cEther_;\n    }\n\n    /**\n     * @notice msg.sender sends Ether to repay an account\u0027s borrow in the cEther market\n     * @dev The provided Ether is applied towards the borrow balance, any excess is refunded\n     * @param borrower The address of the borrower account to repay on behalf of\n     * @return The initial borrows before the repay\n     */\n    function repayBehalf(address borrower) public payable {\n        return repayBehalfExplicit(borrower, cEther);\n    }\n\n    /**\n     * @notice msg.sender sends Ether to repay an account\u0027s borrow in a cEther market\n     * @dev The provided Ether is applied towards the borrow balance, any excess is refunded\n     * @param borrower The address of the borrower account to repay on behalf of\n     * @param cEther_ The address of the cEther contract to repay in\n     * @return The initial borrows before the repay\n     */\n    function repayBehalfExplicit(address borrower, CEther cEther_) public payable {\n        uint received = msg.value;\n        uint borrows = cEther_.borrowBalanceCurrent(borrower);\n        if (received \u003e borrows) {\n            cEther_.repayBorrowBehalf.value(borrows)(borrower);\n            msg.sender.transfer(received - borrows);\n        } else {\n            cEther_.repayBorrowBehalf.value(received)(borrower);\n        }\n    }\n}\n"},"PriceOracle.sol":{"content":"pragma solidity ^0.5.8;\n\nimport \"./CToken.sol\";\n\ninterface PriceOracle {\n    /**\n     * @notice Indicator that this is a PriceOracle contract (for inspection)\n     */\n    function isPriceOracle() external pure returns (bool);\n\n    /**\n      * @notice Get the underlying price of a cToken asset\n      * @param cToken The cToken to get the underlying price of\n      * @return The underlying asset price mantissa (scaled by 1e18).\n      *  Zero means the price is unavailable.\n      */\n    function getUnderlyingPrice(CToken cToken) external view returns (uint);\n}\n"},"PriceOracleProxy.sol":{"content":"pragma solidity ^0.5.8;\n\nimport \"./CErc20.sol\";\nimport \"./CToken.sol\";\nimport \"./PriceOracle.sol\";\nimport \"./Comptroller.sol\";\n\ninterface V1PriceOracleInterface {\n    function assetPrices(address asset) external view returns (uint);\n}\n\ncontract PriceOracleProxy is PriceOracle {\n    /**\n     * @notice The v1 price oracle, which will continue to serve prices\n     * prices for v1 assets\n     */\n    V1PriceOracleInterface public v1PriceOracle;\n\n    /**\n     * @notice The active comptroller, which will be checked for listing status\n     * to short circuit and return 0 for unlisted assets.\n     *\n     * @dev Listed markets are not part of the comptroller interface used by\n     * cTokens, so we assumena an instance of v1 comptroller.sol instead\n     */\n    Comptroller public comptroller;\n\n    /**\n     * @notice address of the cEther contract, which has a constant price\n     */\n    address public cEtherAddress;\n\n    /**\n     * @notice Indicator that this is a PriceOracle contract (for inspection)\n     */\n    bool public constant isPriceOracle = true;\n\n    /**\n     * @param comptroller_ The address of the active comptroller, which will\n     * be consulted for market listing status.\n     * @param v1PriceOracle_ The address of the v1 price oracle, which will\n     * continue to operate and hold prices for collateral assets.\n     * @param cEtherAddress_ The address of the cEther contract, which will\n     * return a constant 1e18, since all prices relative to ether\n     */\n    constructor(address comptroller_, address v1PriceOracle_, address cEtherAddress_) public {\n        comptroller = Comptroller(comptroller_);\n        v1PriceOracle = V1PriceOracleInterface(v1PriceOracle_);\n        cEtherAddress = cEtherAddress_;\n    }\n\n    /**\n     * @notice Get the underlying price of a listed cToken asset\n     * @param cToken The cToken to get the underlying price of\n     * @return The underlying asset price mantissa (scaled by 1e18).\n     *  Zero means the price is unavailable.\n     */\n    function getUnderlyingPrice(CToken cToken) public view returns (uint) {\n        address cTokenAddress = address(cToken);\n        (bool isListed, ) = comptroller.markets(cTokenAddress);\n\n        if (!isListed) {\n            // not listed, worthless\n            return 0;\n        } else if (cTokenAddress == cEtherAddress) {\n            // ether always worth 1\n            return 1e18;\n        } else {\n            // read from v1 oracle\n            address underlying = CErc20(cTokenAddress).underlying();\n            return v1PriceOracle.assetPrices(underlying);\n        }\n    }\n}\n"},"ReentrancyGuard.sol":{"content":"pragma solidity ^0.5.8;\n\n/**\n * @title Helps contracts guard against reentrancy attacks.\n * @author Remco Bloemen \u003cremco@2π.com\u003e, Eenae \[email protected]\u003e\n * @dev If you mark a function `nonReentrant`, you should also\n * mark it `external`.\n */\ncontract ReentrancyGuard {\n    /// @dev counter to allow mutex lock with only one SSTORE operation\n    uint256 private _guardCounter;\n\n    constructor () internal {\n        // The counter starts at one to prevent changing it from zero to a non-zero\n        // value, which is a more expensive operation.\n        _guardCounter = 1;\n    }\n\n    /**\n     * @dev Prevents a contract from calling itself, directly or indirectly.\n     * Calling a `nonReentrant` function from another `nonReentrant`\n     * function is not supported. It is possible to prevent this from happening\n     * by making the `nonReentrant` function external, and make it call a\n     * `private` function that does the actual work.\n     */\n    modifier nonReentrant() {\n        _guardCounter += 1;\n        uint256 localCounter = _guardCounter;\n        _;\n        require(localCounter == _guardCounter, \"re-entered\");\n    }\n}\n"},"SimplePriceOracle.sol":{"content":"pragma solidity ^0.5.8;\n\nimport \"./PriceOracle.sol\";\nimport \"./CErc20.sol\";\n\ncontract SimplePriceOracle is PriceOracle {\n    mapping(address =\u003e uint) prices;\n    bool public constant isPriceOracle = true;\n\n    function getUnderlyingPrice(CToken cToken) public view returns (uint) {\n        return prices[address(CErc20(address(cToken)).underlying())];\n    }\n\n    function setUnderlyingPrice(CToken cToken, uint underlyingPriceMantissa) public {\n        prices[address(CErc20(address(cToken)).underlying())] = underlyingPriceMantissa;\n    }\n\n    // v1 price oracle interface for use as backing of proxy\n    function assetPrices(address asset) external view returns (uint) {\n        return prices[asset];\n    }\n}\n"},"Unitroller.sol":{"content":"pragma solidity ^0.5.8;\n\nimport \"./ErrorReporter.sol\";\nimport \"./ComptrollerStorage.sol\";\n/**\n * @title ComptrollerCore\n * @dev storage for the comptroller will be at this address, and\n * cTokens should reference this contract rather than a deployed implementation if\n *\n */\ncontract Unitroller is UnitrollerAdminStorage, ComptrollerErrorReporter {\n\n    /**\n      * @notice Emitted when pendingComptrollerImplementation is changed\n      */\n    event NewPendingImplementation(address oldPendingImplementation, address newPendingImplementation);\n\n    /**\n      * @notice Emitted when pendingComptrollerImplementation is accepted, which means comptroller implementation is updated\n      */\n    event NewImplementation(address oldImplementation, address newImplementation);\n\n    /**\n      * @notice Emitted when pendingAdmin is changed\n      */\n    event NewPendingAdmin(address oldPendingAdmin, address newPendingAdmin);\n\n    /**\n      * @notice Emitted when pendingAdmin is accepted, which means admin is updated\n      */\n    event NewAdmin(address oldAdmin, address newAdmin);\n\n    constructor() public {\n        // Set admin to caller\n        admin = msg.sender;\n    }\n\n    /*** Admin Functions ***/\n    function _setPendingImplementation(address newPendingImplementation) public returns (uint) {\n\n        if (msg.sender != admin) {\n            return fail(Error.UNAUTHORIZED, FailureInfo.SET_PENDING_IMPLEMENTATION_OWNER_CHECK);\n        }\n\n        address oldPendingImplementation = pendingComptrollerImplementation;\n\n        pendingComptrollerImplementation = newPendingImplementation;\n\n        emit NewPendingImplementation(oldPendingImplementation, pendingComptrollerImplementation);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n    * @notice Accepts new implementation of comptroller. msg.sender must be pendingImplementation\n    * @dev Admin function for new implementation to accept it\u0027s role as implementation\n    * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n    */\n    function _acceptImplementation() public returns (uint) {\n        // Check caller is pendingImplementation and pendingImplementation ≠ address(0)\n        if (msg.sender != pendingComptrollerImplementation || pendingComptrollerImplementation == address(0)) {\n            return fail(Error.UNAUTHORIZED, FailureInfo.ACCEPT_PENDING_IMPLEMENTATION_ADDRESS_CHECK);\n        }\n\n        // Save current values for inclusion in log\n        address oldImplementation = comptrollerImplementation;\n        address oldPendingImplementation = pendingComptrollerImplementation;\n\n        comptrollerImplementation = pendingComptrollerImplementation;\n\n        pendingComptrollerImplementation = address(0);\n\n        emit NewImplementation(oldImplementation, comptrollerImplementation);\n        emit NewPendingImplementation(oldPendingImplementation, pendingComptrollerImplementation);\n\n        return uint(Error.NO_ERROR);\n    }\n\n\n    /**\n      * @notice Begins transfer of admin rights. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.\n      * @dev Admin function to begin change of admin. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.\n      * @param newPendingAdmin New pending admin.\n      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n      *\n      * TODO: Should we add a second arg to verify, like a checksum of `newAdmin` address?\n      */\n    function _setPendingAdmin(address newPendingAdmin) public returns (uint) {\n        // Check caller = admin\n        if (msg.sender != admin) {\n            return fail(Error.UNAUTHORIZED, FailureInfo.SET_PENDING_ADMIN_OWNER_CHECK);\n        }\n\n        // Save current value, if any, for inclusion in log\n        address oldPendingAdmin = pendingAdmin;\n\n        // Store pendingAdmin with value newPendingAdmin\n        pendingAdmin = newPendingAdmin;\n\n        // Emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin)\n        emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n      * @notice Accepts transfer of admin rights. msg.sender must be pendingAdmin\n      * @dev Admin function for pending admin to accept role and update admin\n      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)\n      */\n    function _acceptAdmin() public returns (uint) {\n        // Check caller is pendingAdmin and pendingAdmin ≠ address(0)\n        if (msg.sender != pendingAdmin || msg.sender == address(0)) {\n            return fail(Error.UNAUTHORIZED, FailureInfo.ACCEPT_ADMIN_PENDING_ADMIN_CHECK);\n        }\n\n        // Save current values for inclusion in log\n        address oldAdmin = admin;\n        address oldPendingAdmin = pendingAdmin;\n\n        // Store admin with value pendingAdmin\n        admin = pendingAdmin;\n\n        // Clear the pending value\n        pendingAdmin = address(0);\n\n        emit NewAdmin(oldAdmin, admin);\n        emit NewPendingAdmin(oldPendingAdmin, pendingAdmin);\n\n        return uint(Error.NO_ERROR);\n    }\n\n    /**\n     * @dev Delegates execution to an implementation contract.\n     * It returns to the external caller whatever the implementation returns\n     * or forwards reverts.\n     */\n    function () payable external {\n        // delegate all other functions to current implementation\n        (bool success, ) = comptrollerImplementation.delegatecall(msg.data);\n\n        // solium-disable-next-line security/no-inline-assembly\n        assembly {\n              let free_mem_ptr := mload(0x40)\n              returndatacopy(free_mem_ptr, 0, returndatasize)\n\n              switch success\n              case 0 { revert(free_mem_ptr, returndatasize) }\n              default { return(free_mem_ptr, returndatasize) }\n        }\n    }\n}\n"},"WhitePaperInterestRateModel.sol":{"content":"pragma solidity ^0.5.8;\n\nimport \"./Exponential.sol\";\nimport \"./InterestRateModel.sol\";\n\n/**\n  * @title The Compound Standard Interest Rate Model with pluggable constants\n  * @author Compound\n  * @notice See Section 2.4 of the Compound Whitepaper\n  */\ncontract WhitePaperInterestRateModel is InterestRateModel, Exponential {\n    /**\n     * @notice Indicator that this is an InterestRateModel contract (for inspection)\n     */\n    bool public constant isInterestRateModel = true;\n\n    /**\n     * @notice The multiplier of utilization rate that gives the slope of the interest rate\n     */\n    uint public multiplier;\n\n    /**\n     * @notice The base interest rate which is the y-intercept when utilization rate is 0\n     */\n    uint public baseRate;\n\n    /**\n     * @notice The approximate number of blocks per year that is assumed by the interest rate model\n     */\n    uint public constant blocksPerYear = 2102400;\n\n    constructor(uint baseRate_, uint multiplier_) public {\n        baseRate = baseRate_;\n        multiplier = multiplier_;\n    }\n\n    enum IRError {\n        NO_ERROR,\n        FAILED_TO_ADD_CASH_PLUS_BORROWS,\n        FAILED_TO_GET_EXP,\n        FAILED_TO_MUL_UTILIZATION_RATE,\n        FAILED_TO_ADD_BASE_RATE\n    }\n\n    /*\n     * @dev Calculates the utilization rate (borrows / (cash + borrows)) as an Exp\n     */\n    function getUtilizationRate(uint cash, uint borrows) pure internal returns (IRError, Exp memory) {\n        if (borrows == 0) {\n            // Utilization rate is zero when there\u0027s no borrows\n            return (IRError.NO_ERROR, Exp({mantissa: 0}));\n        }\n\n        (MathError err0, uint cashPlusBorrows) = addUInt(cash, borrows);\n        if (err0 != MathError.NO_ERROR) {\n            return (IRError.FAILED_TO_ADD_CASH_PLUS_BORROWS, Exp({mantissa: 0}));\n        }\n\n        (MathError err1, Exp memory utilizationRate) = getExp(borrows, cashPlusBorrows);\n        if (err1 != MathError.NO_ERROR) {\n            return (IRError.FAILED_TO_GET_EXP, Exp({mantissa: 0}));\n        }\n\n        return (IRError.NO_ERROR, utilizationRate);\n    }\n\n    /*\n     * @dev Calculates the utilization and borrow rates for use by getBorrowRate function\n     */\n    function getUtilizationAndAnnualBorrowRate(uint cash, uint borrows) view internal returns (IRError, Exp memory, Exp memory) {\n        (IRError err0, Exp memory utilizationRate) = getUtilizationRate(cash, borrows);\n        if (err0 != IRError.NO_ERROR) {\n            return (err0, Exp({mantissa: 0}), Exp({mantissa: 0}));\n        }\n\n        // Borrow Rate is 5% + UtilizationRate * 45% (baseRate + UtilizationRate * multiplier);\n        // 45% of utilizationRate, is `rate * 45 / 100`\n        (MathError err1, Exp memory utilizationRateMuled) = mulScalar(utilizationRate, multiplier);\n        // `mulScalar` only overflows when the product is \u003e= 2^256.\n        // utilizationRate is a real number on the interval [0,1], which means that\n        // utilizationRate.mantissa is in the interval [0e18,1e18], which means that 45 times\n        // that is in the interval [0e18,45e18]. That interval has no intersection with 2^256, and therefore\n        // this can never overflow for the standard rates.\n        if (err1 != MathError.NO_ERROR) {\n            return (IRError.FAILED_TO_MUL_UTILIZATION_RATE, Exp({mantissa: 0}), Exp({mantissa: 0}));\n        }\n\n        (MathError err2, Exp memory utilizationRateScaled) = divScalar(utilizationRateMuled, mantissaOne);\n        // 100 is a constant, and therefore cannot be zero, which is the only error case of divScalar.\n        assert(err2 == MathError.NO_ERROR);\n\n        // Add the 5% for (5% + 45% * Ua)\n        (MathError err3, Exp memory annualBorrowRate) = addExp(utilizationRateScaled, Exp({mantissa: baseRate}));\n        // `addExp` only fails when the addition of mantissas overflow.\n        // As per above, utilizationRateMuled is capped at 45e18,\n        // and utilizationRateScaled is capped at 4.5e17. mantissaFivePercent = 0.5e17, and thus the addition\n        // is capped at 5e17, which is less than 2^256. This only applies to the standard rates\n        if (err3 != MathError.NO_ERROR) {\n            return (IRError.FAILED_TO_ADD_BASE_RATE, Exp({mantissa: 0}), Exp({mantissa: 0}));\n        }\n\n        return (IRError.NO_ERROR, utilizationRate, annualBorrowRate);\n    }\n\n    /**\n      * @notice Gets the current borrow interest rate based on the given asset, total cash, total borrows\n      *         and total reserves.\n      * @dev The return value should be scaled by 1e18, thus a return value of\n      *      `(true, 1000000000000)` implies an interest rate of 0.000001 or 0.0001% *per block*.\n      * @param cash The total cash of the underlying asset in the CToken\n      * @param borrows The total borrows of the underlying asset in the CToken\n      * @param _reserves The total reserves of the underlying asset in the CToken\n      * @return Success or failure and the borrow interest rate per block scaled by 10e18\n      */\n    function getBorrowRate(uint cash, uint borrows, uint _reserves) public view returns (uint, uint) {\n        _reserves; // pragma ignore unused argument\n\n        (IRError err0, Exp memory _utilizationRate, Exp memory annualBorrowRate) = getUtilizationAndAnnualBorrowRate(cash, borrows);\n        if (err0 != IRError.NO_ERROR) {\n            return (uint(err0), 0);\n        }\n\n        // And then divide down by blocks per year.\n        (MathError err1, Exp memory borrowRate) = divScalar(annualBorrowRate, blocksPerYear); // basis points * blocks per year\n        // divScalar only fails when divisor is zero. This is clearly not the case.\n        assert(err1 == MathError.NO_ERROR);\n\n        _utilizationRate; // pragma ignore unused variable\n\n        // Note: mantissa is the rate scaled 1e18, which matches the expected result\n        return (uint(IRError.NO_ERROR), borrowRate.mantissa);\n    }\n}\n"}}